Clean install Recalbox 9, default keyboard mappings for "A" is two simultaneous buttons

[catatung]

Hello all,

This has been a source of frustration for hours now. I've got a Double Dragon cabinet, and looking to get it operating via emulation rather than troubleshooting the actual PCB and burning new eproms (it has sound glitches, etc) - I am going to simplify my problem to what I believe is the root of the problem, eliminating my USB Jamma device from the equation.

So, clean install - download IMG file, write it to the storage device, boot up, recalbox does it's partition configuration and sets everything up. Drop in ddragon.zip (the rom file) and restart. Navigate to mame and start it up. The keyboard mappings from what I can tell are the following:

A - P1 punch, P2 Kick
S - P2 Jump
Q - P2 Punch
Z - P1 Kick
X - P1 Jump
Arrow Keys - Move P1
R,F,D,G - Move P2
5 - P1 Coin in
6 - P2 Coin in
1 - P1 Start
2 - P2 Start

My question is -- does anybody know why the "A" key is issuing two buttons to be pressed? (P1 for Punch and P2 for Kick)
This seems absolutely incorrect, especially for a default configuration. If I try and remap the keyboard keys, whenever I try to map the key "A" to anything I get something like "A RP1 Y" however if I map key "B" to something, I get just "B" as expected.

This has been driving me absolutely crazy for many hours now, going on two days. Does anyone have an explanation so I can understand, or is this some kind of a bug induced by the specific hardware I have (would be hard to believe but nothing seems to make sense to me in this problem anyway..)

Any help would be very much appreciated.
Thanks for any thoughts, advice or suggestions...