As part of a remodel, we are reducing the size of a window opening. It has a double double-hung sash window about 6 x 4-1/2 feet (two windows side by side, separated by wood support, originally delivered and installed as one unit). Instead of removing the old window and replacing it with a new, smaller one, the contractor says he can take out the old window and cut it in half. I never heard of this before. Is this a wise move? This is an 18-year good quality, Anderson window. I am not sure if it is all vinyl, or vinyl-clad.