replacing timing chain on 93 sentra

someone told me there was an upper and lower timing chain. is that true. how much should it cost to replace thanks

If it is the 1.6l engine then yes, I actually think it is 3 sets, but not positive since it has been a couple years since I replaced mine. There are also a set of tenstioners that need to be replaced at the same time.
Parts were close to 200 for me, so expect to pay 400-600 depending on labor costs. Book time says 12 hours.

Yeah, don't count on any less than $500.