If you are assuming they are zinc because they leaked I'm afraid that's not necessarily so. I've had many alkaline cells leak, though generally well past their expiry date despite still working.
The Rockets in one of ours are currently a year past their date but still look OK (they've been in use for nearly three years). They are labelled 'heavy duty' with no Mercury or Cadmium, but under the bin with a cross symbol there is 'Pb'. Maybe they are lead-acid
Batteries in our remotes seem to last forever and I have to make an effort to inspect them once in a while for mankiness since that often precedes failing to power the device.
Two years for alkalines or zinc chlorides in a TV remote is very low. You must be hammering it. I'd expect any alkalines to last in a remote until they die of age (e.g. leak). Even with zinc chloride on my main remote (HDR-FOX T2 used for amplifier and TV as well) I expect them to last until they die of old age rather then being just all used up.
GP zinc are easily available. Are you sure that they are alkaline? I think at one time they looked very similar.
I've found that I notice a drop-off in range, in that you can no longer just point in the general direction of the device, at around the 12 months mark with TVs and the old '9200. The HDR's remote doesn't do this until around 2 years.