You’re welcome, Charlie!
Your explanation of how you’re using it has inspired me to suggest a way to operate the two signals separately, each when the train is across its own street. To do this, the KW transformer that you’re powering the signals with may have none of its terminals connected to the track. If that’s the case in your setup, all you will need is your second flasher module and two diodes.
Instead of connecting the transformer directly to the track, instead connect the negative terminal of the rectifier (and capacitor) to the outside rails generally. Then power each flasher-signal combination by connecting the flasher X terminal to the positive terminal of the rectifier (and capacitor) and the lamp common to one of the outer (insulated) control rails. This will cause each signal to flash independently when the train is on the outer control-rail section on its side of the streets. Finally, connect each of those outer control rails to the one center control rail through a diode, with each diode’s cathode connected to the center control rail. (The cathode is the end with the ring around it.) Suitable diodes are any of the 1N4001 through 1N4007. Now each signal will flash just when the train is close to its own street; so the flashing will start and stop at different times for each signal, which seems to me to be a more interesting operation.