are on IMVU just to meet the opposite gender anyway
Yes. It's a chat program so you'll have the vast amounts of people who mainly use it to "meet" the opposite gender.
If a person you don't know invites you that's using the same gender avatar and leaves because of it
you should have known before hand.
People mostly do that for anonymous "meeting". I have a Chatango messenger on my page.
The vast majority of PMs that I get on it are from people who just found me(my profile has a sexy panda in her undies) in the search feature
and want to "meet" with me.