I've picked up two (presumably used) keys from eBay both working at a low price from the same seller.
The keys apparently were 2001, and look the same.
My car is 2001 LS430, UCF30R-AEAGKW; Europe, Right hand drive, 3UZFE, 5 speed automatic, and apparently Ultraluxury edition (but without parking sensors).
Is there a way to program these to start the car and function identical or similar to the only master key I have?
Picture attached. Left to right; Purchased key 1, Purchased key 2, Functioning master key.
You are still too vague. Get the hood open, have someone rev the car up several times while you stand in front of the car and determine where the sound appears to originate.
Better yet, record a sound clip or video on your phone and post it here.