Hinged Beam Reaction Forces

Yes. Consult any textbook on Statics.

statics books assume one hinge and one roller support to reduce the number of unknowns

can we assume the same in the design of pinned connections?

Only if the beam is not sagging either under its own weight or that of an applied load.

since the load is at center and the beam is symmetrical in shape why the forces on both hinges is not considered equal?

It can't be seen from here; without a sketch it is anyone's guess.

Under "normal" assumptions, if W is the weight of a symmetrical beam, and an additional force P is imposed at the center, the reaction at each end will be F = (W+P)/2.

If the beam is restrained between solidly fixed ends, then thermal expansion/contraction, or sagging, may result in considerably larger forces. In that case, we need to know the "hinge" details.

F=(W+P)/2 is this the resultant force?

If the beam is restrained between solidly fixed ends, then thermal expansion/contraction, or sagging, may result in considerably larger forces.

The Force must be with me today--I say something and it is repeated. I don't suppose this quotable gem will get into Bartlett's, though.

well, gentlemen what I believed that either the owner's question is student try to understand his homework or someone did not have a glue on mechanical engineering basic. If I am correct than I would suggest that he or she should go through the static book before come back with more questions.