This house had a double wooden entry door, each door being about 40"
wide. One is rarely used; the other is for everyday use. The everyday
door is bowed at the latch side toward the inside of the house by about
1/8-3/16". (The hinge side is okay.) So to engage the latch and
deadbolts into their strike plates, one must push the lock area really
hard toward the outdoors or slam the door closed hard.

The first thing I will try doing is repositioning the door stops. I've
read several methods for reversing the warp, and may try one of those
measures.

The real question is why should just one of the doors warp? Both are
exposed to the same temperature differentials. Both doors have outer
storm doors with glass panels during New Jersey's winter season. The
colors on both sides of both doors match, but I can't guarantee that
both sides of both doors are painted with the same type paint (latex vs.
oil). The house was built in 1993.

R1