Here is a General Manager (an employee) who needs to execute a Contract with the third Party. The President of the Company issued a Power of Attorney to such General Manager stating in the Power of Attorney his name and title as 'General Manager' to authorize him to execute the Contract. In this Case, is it necessary for the General Manager to state his title (if the space in the Contract so requires) as 'Attorney-in-fact' or is it permissible for him to state his tile as 'General Manager'?
If the Power of Attorney states his name and title as General Manager, then he should only sign as his name and his title. Furthermore, he should also state as "Attorney-in-fact" for "Principals' name" otherwise it is as though he (General Manager) himself is signing and obligated under the contract rather then the Principal on whose behalf he is intending to act.

The signature should therefore read, "General Manager's name + General Manager Title + as Attorney-in-fact (sometimes agent) for + Principal's Name."
The one who signs the document should NOT use a title that is not his - this could void everything. The "Attorney-in-Fact" should sign it as himself with POA from the GM.

I've only been in contracting for 23 years, but then, what do I know?

Word of advise - if there is ever a doubt, err on the side of caution. Contracts bite both ways.
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 KJinCali79's reply was promoted to an answer.
With respect to the second sentence, do you mean that the Attorney-in-fact should sign it as himself with POA from the principal (not from GM)?