Humax HDR remote control oddity

I have a wireless IR extender and notice that the HDR doesn't respond via this route unless you press the remote key twice quickly in succession, and it's very hit-and-miss as to exactly how quickly you press. This also occurs with one other item of equipment I have. Having read up a bit about it, I understand that some remote controls transmit the same code several times in succcession when you press a button, and therefore the equipment is designed to handle this. Perhaps the various IR extenders only relay one occurrence of the code, which is why they don't work for these items of equipment. Am I on the right lines?