diff --git a/server/src/calendardb/optiondb-lmdbx.ts b/server/src/calendardb/optiondb-lmdbx.ts
index 60af0c9..5fbc747 100644
--- a/server/src/calendardb/optiondb-lmdbx.ts
+++ b/server/src/calendardb/optiondb-lmdbx.ts
@@ -68,14 +68,22 @@ function makeCalendarDatabase(): CalendarDatabase {
       return optionContracts.flatMap(
         (frontOptionContract, i, optionContracts) =>
           optionContracts
-            .filter((_, j) => i !== j)
+            .filter(
+              (potientialBackOptionContract) =>
+                frontOptionContract.strike ===
+                  potientialBackOptionContract.strike &&
+                frontOptionContract.type ===
+                  potientialBackOptionContract.type &&
+                frontOptionContract.expirationDate <
+                  potientialBackOptionContract.expirationDate
+            )
             .map((backOptionContract) => ({
               symbol,
               frontExpirationDate: frontOptionContract.expirationDate,
               backExpirationDate: backOptionContract.expirationDate,
               strike: frontOptionContract.strike,
               type: frontOptionContract.type,
-            })),
+            }))
       );
     },
     getAggregates: async ({