diff --git a/lib/dsn-pcb/dsn-json-to-circuit-json/convert-dsn-session-to-circuit-json.ts b/lib/dsn-pcb/dsn-json-to-circuit-json/convert-dsn-session-to-circuit-json.ts
index a179fe0..de5639e 100644
--- a/lib/dsn-pcb/dsn-json-to-circuit-json/convert-dsn-session-to-circuit-json.ts
+++ b/lib/dsn-pcb/dsn-json-to-circuit-json/convert-dsn-session-to-circuit-json.ts
@@ -72,6 +72,10 @@ export function convertDsnSessionToCircuitJson(
 
   const sessionElements: AnyCircuitElement[] = []
 
+  // Track via positions globally to deduplicate across all nets.
+  // Maps "x,y" -> net name that first claimed the via.
+  const addedViaKeys = new Map<string, string>()
+
   // Process nets for vias and wires
   for (const net of dsnSession.routes.network_out.nets) {
     // Find corresponding source trace for this net
@@ -120,6 +124,19 @@ export function convertDsnSessionToCircuitJson(
         const viaX = Number(viaPoint.x.toFixed(4))
         const viaY = Number(viaPoint.y.toFixed(4))
 
+        // Skip duplicate vias at the same coordinates
+        const viaKey = `${viaX},${viaY}`
+        const existingNet = addedViaKeys.get(viaKey)
+        if (existingNet) {
+          if (existingNet !== net.name) {
+            console.warn(
+              `[dsn-converter] Via at (${viaX}, ${viaY}) claimed by net "${existingNet}" also appears in net "${net.name}" — possible short circuit in routing`,
+            )
+          }
+          return
+        }
+        addedViaKeys.set(viaKey, net.name)
+
         // Find the wire points that connect to this via across all route segments
         const connectingWires = sessionElements
           .flatMap((segment) =>
diff --git a/tests/repros/repro15-duplicate-vias.test.ts b/tests/repros/repro15-duplicate-vias.test.ts
new file mode 100644
index 0000000..6f9f4c6
--- /dev/null
+++ b/tests/repros/repro15-duplicate-vias.test.ts
@@ -0,0 +1,212 @@
+import { expect, test } from "bun:test"
+import { convertDsnSessionToCircuitJson } from "lib/dsn-pcb/dsn-json-to-circuit-json/convert-dsn-session-to-circuit-json"
+import type { DsnPcb, DsnSession } from "lib/dsn-pcb/types"
+
+test("duplicate vias from freerouting session are deduplicated", () => {
+  // Minimal DsnPcb input with two layers and one net
+  const dsnPcb: DsnPcb = {
+    is_dsn_pcb: true,
+    filename: "test.dsn",
+    parser: {
+      string_quote: '"',
+      host_version: "test",
+      space_in_quoted_tokens: "on",
+      host_cad: "test",
+    },
+    resolution: { unit: "um", value: 10000 },
+    unit: "um",
+    structure: {
+      layers: [
+        { name: "F.Cu", type: "signal", property: { index: 0 } },
+        { name: "B.Cu", type: "signal", property: { index: 1 } },
+      ],
+      boundary: {
+        path: {
+          layer: "pcb",
+          width: 0,
+          coordinates: [0, 0, 100000, 0, 100000, 100000, 0, 100000],
+        },
+      },
+      via: "Via[0-1]_600:300_um",
+      rule: { clearances: [{ value: 200 }], width: 250 },
+    },
+    placement: { components: [] },
+    library: { images: [], padstacks: [] },
+    network: { nets: [], classes: [] },
+    wiring: { wires: [] },
+  }
+
+  // Session with duplicate vias at the same coordinates within one net
+  const dsnSession: DsnSession = {
+    is_dsn_session: true,
+    filename: "test.ses",
+    placement: {
+      resolution: { unit: "um", value: 10000 },
+      components: [],
+    },
+    routes: {
+      resolution: { unit: "um", value: 10000 },
+      parser: {
+        string_quote: '"',
+        host_version: "test",
+        space_in_quoted_tokens: "on",
+        host_cad: "test",
+      },
+      library_out: {
+        images: [],
+        padstacks: [
+          {
+            name: "Via[0-1]_600:300_um",
+            shapes: [
+              { shapeType: "circle", layer: "F.Cu", diameter: 600 },
+              { shapeType: "circle", layer: "B.Cu", diameter: 600 },
+            ],
+            attach: "off",
+          },
+        ],
+      },
+      network_out: {
+        nets: [
+          {
+            name: "TestNet",
+            wires: [
+              {
+                path: {
+                  layer: "F.Cu",
+                  width: 250,
+                  coordinates: [10000, 20000, 30000, 20000],
+                },
+              },
+              {
+                path: {
+                  layer: "B.Cu",
+                  width: 250,
+                  coordinates: [30000, 20000, 50000, 20000],
+                },
+              },
+            ],
+            // Freerouting sometimes outputs duplicate vias at the same location
+            vias: [
+              { x: 30000, y: 20000 },
+              { x: 30000, y: 20000 }, // duplicate
+              { x: 30000, y: 20000 }, // another duplicate
+            ],
+          },
+        ],
+      },
+    },
+  }
+
+  const result = convertDsnSessionToCircuitJson(dsnPcb, dsnSession)
+
+  const pcbVias = result.filter((el) => el.type === "pcb_via")
+
+  // Should only have 1 via even though 3 were in the input
+  expect(pcbVias.length).toBe(1)
+})
+
+test("duplicate vias across different nets are deduplicated", () => {
+  const dsnPcb: DsnPcb = {
+    is_dsn_pcb: true,
+    filename: "test.dsn",
+    parser: {
+      string_quote: '"',
+      host_version: "test",
+      space_in_quoted_tokens: "on",
+      host_cad: "test",
+    },
+    resolution: { unit: "um", value: 10000 },
+    unit: "um",
+    structure: {
+      layers: [
+        { name: "F.Cu", type: "signal", property: { index: 0 } },
+        { name: "B.Cu", type: "signal", property: { index: 1 } },
+      ],
+      boundary: {
+        path: {
+          layer: "pcb",
+          width: 0,
+          coordinates: [0, 0, 100000, 0, 100000, 100000, 0, 100000],
+        },
+      },
+      via: "Via[0-1]_600:300_um",
+      rule: { clearances: [{ value: 200 }], width: 250 },
+    },
+    placement: { components: [] },
+    library: { images: [], padstacks: [] },
+    network: { nets: [], classes: [] },
+    wiring: { wires: [] },
+  }
+
+  const dsnSession: DsnSession = {
+    is_dsn_session: true,
+    filename: "test.ses",
+    placement: {
+      resolution: { unit: "um", value: 10000 },
+      components: [],
+    },
+    routes: {
+      resolution: { unit: "um", value: 10000 },
+      parser: {
+        string_quote: '"',
+        host_version: "test",
+        space_in_quoted_tokens: "on",
+        host_cad: "test",
+      },
+      library_out: {
+        images: [],
+        padstacks: [
+          {
+            name: "Via[0-1]_600:300_um",
+            shapes: [
+              { shapeType: "circle", layer: "F.Cu", diameter: 600 },
+              { shapeType: "circle", layer: "B.Cu", diameter: 600 },
+            ],
+            attach: "off",
+          },
+        ],
+      },
+      network_out: {
+        nets: [
+          {
+            name: "Net1",
+            wires: [
+              {
+                path: {
+                  layer: "F.Cu",
+                  width: 250,
+                  coordinates: [10000, 20000, 30000, 20000],
+                },
+              },
+            ],
+            vias: [
+              { x: 30000, y: 20000 },
+              { x: 50000, y: 40000 },
+            ],
+          },
+          {
+            name: "Net2",
+            wires: [
+              {
+                path: {
+                  layer: "F.Cu",
+                  width: 250,
+                  coordinates: [30000, 20000, 60000, 20000],
+                },
+              },
+            ],
+            // Same coordinates as Net1's first via
+            vias: [{ x: 30000, y: 20000 }],
+          },
+        ],
+      },
+    },
+  }
+
+  const result = convertDsnSessionToCircuitJson(dsnPcb, dsnSession)
+
+  const pcbVias = result.filter((el) => el.type === "pcb_via")
+
+  // Should have 2 unique vias (30000,20000) and (50000,40000), not 3
+  expect(pcbVias.length).toBe(2)
+})