1974 comaro 350 two bolt Mains Rear Main seal

I have relaced the rear main seal on my engine. The old seal was a single lip. The new seal went in with no problem in fact it slid in without the air of the shoe. I noticed when I bought the seal there were thre types single lip, Double lip and double offset lip. I know the physical difference of the seals I just don't understand the different applications. I am wondering if I got the wrong seal installed in my engine. (Single Lip) If someone could educate me on the different applications I sure would appreciate it.