If two antennas are placed right next to each other, will they interfere with each other?

If two antennas that are supplied with power are placed right next to each other, will they interfere with each other? The gap between them is about 1 cm.

better keep always a good distance from each other

In general I’d keep them apart, if possible. However, if they are not using the same frequencies, then you might get away with it.