As you suspect the problem stems from IR protocols like RC5 that have a toggle bit. This bit alternates with every button press in the OEM remote. So sending two successive button presses of the SAME button will not be seen by the IR receiver in your equipment as a new command. This should not be a problem with two different buttons. 111 is a problem (all it thinks it sees is 1) but 121 should work fine.
The easiest way to solve the toggle bit problem is to generate one set of codes with the "default" rc5.irp file and make a second irp file, rc5-1.irp and add this statement:
Define=T as 1
Then you will have both sets of codes. Back to the example of selecting channel 111. That would take a 1 from the "default" or Zero case, then a One from T=1, and a 1 from the Zero case.
When you test all 128 commands you probably will find plenty that do nothing. You can execute a "nothing" command between legitimate commands as long as timing isn't important. That should reset the toggle bit.
AFAIK, the only reason you need to use two sets of codes would be to do a macro with two successive button pushes of the SAME key but it is possible that your gear works differently than most. So it might record the last toggle state of EVERY command. If so all multiple commands would need to be done like 111.
Also, most IR receivers only keep the toggle state of the prior command for a few seconds.
So, yes you should be able to do a macro for keys that you want to repeat by holding down by alternating the toggle states. However, I always thought keys like Vol+/- were exempted from the toggle bit logic.
If you do need that macro, you will probably need to experiment with timing between those commands. If too short of an interval, then the Volume or channel may move too fast.
If the T2's editor doesn't allow for programming variable delays, you could tinker with the protocol file (rc5.irp or rc5-1.irp).
Message Time=113778 means that the total IR command will be 113,778 uSec or millionths of a second so changing that value to 213,778 would add a tenth of a second more between commands.
It is also possible that the macro takes too long to execute. So you also might have to shorten the interval if you want quicker response.
BTW, the '128 times TimeBase of 888.89 is a comment and make hex ignores anything with a " ' " in front. So if you start editing this a lot to vary the timing you can erase that whole comment lest that important " ' " get lost and the program bomb.
