Question about tecs

If you place one tec over another, would you have double the cooling power? Lets say your spare PSU doesn't have enough amps on one 12v rail to run a 26amp tec, but has multiple 12v rails. If you use two 200w tecs one ontop of the other, would it be the same in terms of cooling as running one 400w tec?

as far as i know:
you hav to put a more powerfull one ontop of the lower one to draw the heat from that one.
so if you have a cpu putting out 100watts and you want to cool it with two tec the first one would probably be 200w then the one ontop of that has to deal with the heat from both the other sources so it would have to be around 300+ watts.

im no expert with TECs so hopefully someone else can give you a more definite and detailed answer and if im wrong please correct me.

Tecs need to staying within their operating parameters and you will lose efficiency but multiple tec systems are possible. But as SAM__ said, because the second tec has to cool both the load and the first tec it will be hard to do so if you are current limited.