You will have to be more clear with your description of the problem.
NewBiee wroteNow what i want is that vpn 1 and vpn 2 will have the same user accounts in connecting the vpn.
How do your clients connect to the VPN, and what is the purpose in accessing the vpn -- is it a tunnel, or do they access shared resources?
NewBiee wroteI use the "useradd username" command.
useradd will give them access to the shell on the
VPS -- I thought you said you want to give them access to
VPN..
Forgive me for not understanding what you want right now, but if you try say it again using different words, it may be possible to try help you with a solution. So, rephrase if you may.