diff --git a/server/handlers.go b/server/handlers.go
index 7959770..f506bc1 100644
--- a/server/handlers.go
+++ b/server/handlers.go
@@ -33,12 +33,13 @@ func (s *Server) handleEventEthNewHeader(
 
 	block := header.Number
 	blockStr := block.String()
+	blockHash := header.Hash()
 
 	g := s.state.ExecutionGroup(gname)
 	e := g.Endpoint(ename)
 
 	e.RegisterBlock(block, ts)
-	latency := g.RegisterBlockAndGetLatency(block, ts)
+	latency := g.RegisterBlockAndGetLatency(block, blockHash, ts)
 	latency_s := latency.Seconds()
 
 	switch latency {
diff --git a/state/el_group.go b/state/el_group.go
index 9125889..fbf4128 100644
--- a/state/el_group.go
+++ b/state/el_group.go
@@ -6,6 +6,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/flashbots/node-monitor/utils"
 )
 
@@ -25,8 +26,9 @@ type ELGroup struct {
 	blocks     *utils.SortedStringQueue
 	blockTimes map[string]time.Time
 
-	highestBlock    *big.Int
-	highestBlockStr string
+	highestBlock     *big.Int
+	highestBlockHash common.Hash
+	highestBlockStr  string
 
 	mx sync.RWMutex
 }
@@ -72,24 +74,24 @@ func (g *ELGroup) Endpoint(name string) *ELEndpoint {
 	return g.endpoints[name]
 }
 
-func (g *ELGroup) RegisterBlockAndGetLatency(block *big.Int, ts time.Time) time.Duration {
-	g.mx.RLock()
-	defer g.mx.RUnlock()
+func (g *ELGroup) RegisterBlockAndGetLatency(block *big.Int, blockHash common.Hash, ts time.Time) time.Duration {
+	g.mx.Lock()
+	defer g.mx.Unlock()
 
 	blockStr := utils.Bigint2string(block)
 
-	// update the highest block (if needed)
-	if blockStr > g.highestBlockStr {
-		g.mx.RUnlock()
-		g.mx.Lock()
-		if blockStr > g.highestBlockStr {
-			delete(g.blockTimes, g.blocks.InsertAndPop(blockStr))
-			g.highestBlock = big.NewInt(0).Set(block)
-			g.highestBlockStr = blockStr
+	if blockStr == g.highestBlockStr {
+		if blockHash != g.highestBlockHash {
 			g.blockTimes[blockStr] = ts
+			g.highestBlockHash = blockHash
 		}
-		g.mx.Unlock()
-		g.mx.RLock()
+		// update the highest block (if needed)
+	} else if blockStr > g.highestBlockStr {
+		delete(g.blockTimes, g.blocks.InsertAndPop(blockStr))
+		g.highestBlock = big.NewInt(0).Set(block)
+		g.highestBlockStr = blockStr
+		g.highestBlockHash = blockHash
+		g.blockTimes[blockStr] = ts
 	}
 
 	prevTS, exists := g.blockTimes[blockStr]