2 tape decks- 1 tape monitor loop

Hello, I have 2 tape decks I want to hook up to my pre that only has connections for 1. There is 1 set of tape out and 1 set of tape in along with several other inputs of which 2 aux's are not being used. The (amp) outputs are all used up. There is a tape selector on my pre that is labeled off, tape and monitor. I plan to record and play back with both decks, but never use them (or have them on) at the same time. I don't plan to record from one deck to the other but do plan to record from CD, phono or tuner onto one tape deck or the other.
My question is, should I use a 2 in 1 Y connector to the set of tape in's and tape out's, or is there a better way to hook these up?