The MCE protocol has a toggle bit whch can have values of 0 or 1.   I generated Pronto Hex for toggle = 0 and you did it for toggle = 1 (Define T=1 in the irp file).
Some devices which receive MCE pay attention to the toggle bit, and only respond if it changes state on each button press.  You'll probably find that any other IR command issued between two identical Ch+ signals will have the effect of resetting the toggle state.  
Systems which depend on learning IR signals typically have quite a bit of trouble with toggling IR protocols.  You may be able to work around it by setting up macros so that pressing Ch+ actually sends the CH+ IR signal, followed by another unimportant IR signal.  Probably there are other ways, but I don't have experience with remotes that need to learn signals.