Your phones BT will only pair with one BT receiver at once.. You can't pair with two BT speakers even if they are the same model.
You could use a stereo pair of BT speakers (there would be a wire from one to the other) since those would only have one receiver for both.
If you were in a home situation you could add an external BT transmitter that could pair with different speakers. You could get double mono not stereo with this arrangement. On a bike this is not an option.