What kind of flange is this?

I am replacing a toilet that has had some leakage issues for years. In the past I have had someone else deal with it so I have never seen what was under the toilet. The flange looks to be some sort of offset flange but nothing I have ever seen before. I don't see how a normal wax ring can seal on this. What do I have here? Thanks for the help!

It's an offset flange.
You drop down a wax ring or two and set the bowl over it.

This would have been a better offset flange

OK, I'll give it a shot. The way the flange gets sort of skinny at the back had me concerned. Thanks.