YA SF novel with a remote control for parallel universe jumping

Question

When I was a kid I read a sci-fi novel for children, the full name of which is unfortunately not coming back to me. Here's what (I think) I remember:

• the story features a handheld device that allows one to jump into some kind of parallel universe
• not 100% sure, but I think it was just one parallel universe, with "evil twin" versions of the main characters
• the cover had a picture of the device on it, which may have looked vaguely like a ColecoVision controller
• it's probably from the early '90s
• I think the title is Strange ________

Answer 1

Found it with your help, Valorum, thank you!

It was Strange Attractors by William Sleator.

Apparently the device was a modified calculator, and it was used for time travel (which leads to a split timeline and antagonist versions of two of the main characters).