RF doorbells as wireless switchs triggering together

Having a bit of trouble trying to use two of these RF doorbells, with only one no problem. Got the pulse from both alone alright but when they are connected to the same circuit (I bet it needs some kind of filter but I don't really know yet) seams the RF or the pulse or I don't know what triggers them both with any of the remotes.

Any help welcomed.

Thanks.

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The test with the remotes was to close... like 1 meter or 2 apart from the receiver. TOO CLOSE! Needs like 5 meters for the signal not to mix.