Is the following scenario illegal?

Mon morning - PHL->ATL on part 1/2 of tix A
Mon evening - ATL->PHL on pt 1/2 of tix B

Tue morning - PHL->ATL on pt 2/2 of tix B
Tue evening - ATL->PHL on pt 2/2 of tix A

I'm looking to do some segment runs for Silver/Gold medallion, but don't want to get flagged as doing something illegal. If the fares permitted return on the same day, and I could get all of the flights in, would that also be legal/illegal?

Thanks.

Jeff