SOLVED. Book about twin boys forced to act as one person. [s]

[Tracy]

The mother got pregnant, I don't recall if it was out of wedlock or what, but she went away to have the baby. She told people she was going abroad to adopt a child as a cover story. She had twins and to maintain said story she forced them to act as one person. She made them speak to each other in first person. IE: Do I want to play with me. One or both of them murdered people. I also seem to remember them being from a wealthy family. There was a movie as well. I read this probably 30 years ago. I have searched every way I can think of. FYI Dead Ringer isn't it. Thanks!

[Escape Into Reading]

Whispers by Dean Koontz

[Tracy]

Jolie wrote: "Whispers by Dean Koontz"
Yes! Thank You!