Drop duplicate requestID jobs

Subscription messages are delivered at least once which might confuse the monitor.

cmd/chainlink_exporter/aggregator.go

@@ -17,6 +17,8 @@ type (
 
 		pendingJobs map[string]*abi.OracleOracleRequest
 
+		seenRequestIDs map[string]bool
+
 		monitor *Monitor
 		lock    sync.Mutex
 	}
@@ -24,10 +26,11 @@ type (
 
 func NewAggregatorMonitor(agg *abi.Aggregator, addr common.Address, m *Monitor) *AggregatorMonitor {
 	return &AggregatorMonitor{
-		aggregator:  agg,
-		pendingJobs: map[string]*abi.OracleOracleRequest{},
-		monitor:     m,
-		address:     addr,
+		aggregator:     agg,
+		pendingJobs:    map[string]*abi.OracleOracleRequest{},
+		seenRequestIDs: map[string]bool{},
+		monitor:        m,
+		address:        addr,
 	}
 }
 
@@ -81,8 +84,17 @@ func (a *AggregatorMonitor) HandleNewBlock(height uint64) {
 func (a *AggregatorMonitor) handleRequest(res *abi.OracleOracleRequest) {
 	a.lock.Lock()
 	defer a.lock.Unlock()
+	requestIDString := hex.EncodeToString(res.RequestId[:])
+	if _, exists := a.seenRequestIDs[requestIDString]; exists {
+		zap.L().Info("request dropped; already seen same reqID", zap.Uint64("height", res.Raw.BlockNumber),
+			zap.String("requester", res.Requester.String()), zap.Binary("request_id", res.RequestId[:]),
+			zap.ByteString("spec_id", res.SpecId[:]), zap.Uint64("request_height", res.Raw.BlockNumber))
+		return
+	} else {
+		a.seenRequestIDs[requestIDString] = true
+	}
 
-	a.pendingJobs[hex.EncodeToString(res.RequestId[:])] = res
+	a.pendingJobs[requestIDString] = res
 }
 
 func (a *AggregatorMonitor) handleFulfillment(res *abi.AggregatorChainlinkFulfilled) {