Interference of 2 Bluetooth Modules, top and bottom of PCB

If I have 2 bluetooth mates that SPARKFUN sells, one on the top of my custom PCB, the other on the bottom side, so that their chip antennas are located opposite one another, will they still function fairly well? I only need about 15 feet of distance from both of them.

I use the (very cheap) HC-07 BT modules, I have two of them on the same breadboard, their antenna are almost touching each others, and no interference problems, both sending messages to Serial Monitors every seconds, not a single error since 15 minutes.

So I suppose it should also work fine with those sparkfun modules ;)

Thanks, good to know. I don't have 2 yet, so I couldn't test it out, but I figured it'd work okay.