Reg requesting concurrent programme more no of time without completing request,it create duplicate s

Hai,User submitting concurrent programme  more no of time without completing request.
They concurrent programme :HMI: Dealer Label Generation Program.
This Programme is customize concurrent programme.
This programme print label based on sequence no from table.
The table will have last sequence no.we will increment sequence for each label .
while printing label duplicate sequence no is coming.
it is coming some time only.i check programme is working fine.
this problem is coming while user submitting concurrent programme more no of time without completing request.
I told we can go for incompatibility for that concurrent programme.
they are saying,it make slow of execution of concurrent prograame.