1) The OEM battery was probably fresher than the one that wound its way through retail distribution and then sat in a drawer at your house for longer than you realize
2) By the time you have to replace a battery, your remote's PCB has had time to adsorb water and contaminants from the air, get soda spilled on it, etc and is going to have higher leakage. It will then always draw more current in standby.
1) The OEM battery was probably fresher than the one that wound its way through retail distribution and then sat in a drawer at your house for longer than you realize
2) By the time you have to replace a battery, your remote's PCB has had time to adsorb water and contaminants from the air, get soda spilled on it, etc and is going to have higher leakage. It will then always draw more current in standby.