It will do this if LEDs are installed in both sockets or if one socket is empty & the other has an LED installed. No dimmers installed just a dumb switch that operates 2 fixtures (other fixture has standard PAR38 bulbs). Another fixture (separate switch) on the back side of the house does not have this issue. It has an LED in one socket & the other is standard PAR38 bulb.
Thoughts as the issue?
You might see if you can put an old-school night light bulb in the other fixture socket to mask your issue.
I have the same problem and hear a relay click when the light goes on, so it's not like it's going through a MOSFET or anything, or maybe it is-- they're pretty cheap inside.
When LEDs first got cheap ~5 years ago I got some actual Cree branded ones that take 1/2 second to stop making light after I shut them off. (They were really trying to mimic incandescent quality.) They may have better rectifiers inside which would again mask your issue.
What's your target here, are you trying to save electricity? How many minutes are these lights on per day and what's the payback?