if your airport not a HUB for Airline company,
inbound flight number and it’s return (outbound) flight numbers should have consecutive flight numbers.
for example I have (same aircraft) inbound flight number is GW813 (shown pic 1 as baggage ticket) and return (outbound) flight has flight number GW814 (shown pic 3)
but if you see pic 2, a passenger that comes with GW813 has a baggage ticket with GW814. it should be GW813, beacuse he was the passenger that inbound (he came)