How about Ronnie and Dexter?
Ronnie competed in 1994, then from 1996 through to 2007. Maybe 1992, but I can't recall. I think...never mind...www.musclememory.
com is your friend.
Dexter for sure had over 13 entries in the Mr. Olympia. He competed from 1999 through to 2018, with the only exception being in 2005...and he actually qualified in 2005, but didn't compete for some reason. That was the year that Gunter Schlierkamp managed to slide into 4th place. In hindsight, Gunter retired from bodybuilding somewhat young - age 36 - and likely able to live a better life now as a result, without having to still tax his body. Gunter will be 49 in January.