Most emulsions are water based, whether it be Matt or silk, so yes it will be OK. I found this out from a painter and decorator cause i had to do the same. If one is oil based and the other water...
Q.what is emulsion? ans) ''If a mixture two partially miscible or immiscible liquids is shaken, a coarse dispersion of one liquid in the other is obtained which is called emulsion'' (Nexus Boys)