
Prior to 2017: Ladder and Non-Ladder shared IPs, yes. Everyone used cheap NL sojs to spawn L clones.
June 2017: Blizzard separated L from NL. They did not share IPs. Everyone was forced to use expensive L sojs to spawn L clones, and the price of anni sky-rocketed as a result.
July 2020: I discovered a way to use NL sojs to spawn L clones again. Dropping the price of anni. (See here for explanation:
https://forums.d2jsp.org/topic.php?t=83622846&f=240 )
So technically no, they're separate, but NL sojs can still be used, if you're willing to camp an IP for days or weeks.