If you have the same IP as someone else, that means you're on the same computer (or even the same LAN I believe). So if two people in the same house are sharing a computer, they'll have the same IP. Obviously though, there could be some suspicion that they're one person using the same account.
That said, as far as I know, nobody at TPM seriously thinks that you are the same person as anyone else here. If this really is a non-TPM-related issue, then I suggest you take it to wherever you are having this problem and work it out with them.
We at TPM are happy to help with any problems you are having with other members here at TPM. Your problems at other forums, however, belong at those forums.