Hi folks,
To confirm what nime5ter said: two Amulet's on a single receiver is not supported at present.
It's actually an interesting idea -- multiple transmitters, one receiver, for the scenario described and in principle, the underlying radio chipset would actually support it. We certainly haven't tested it, but it may be possible to pair two units to the one receiver.
There is also a "public broadcast" mode where the receiver will accept transmissions from any Amulet within range, but our firmware currently doesn't enable this (too problematic if you have two independent Amulet setups operating in close proximity).
More generally, we have a limitation in that our firmware is not field upgradable at present. This is actually No. 1 on my personal list of things to fix, though it's by no means straightforward. Nonetheless, it would open up a lot of scope for adding features, improving IR performance, etc.
However, one step at a time: as discussed elsewhere, we need to get more basic stuff like reliable shipping working first!
Eddy
Amulet Devices