That way they don't pick up the same cat twice.
Trouble is they don't always release the cat into its own territory again..as they are supposed to ! So it starts another turf war with another bunch of cats, who howl, and someone rings the police, who call the vet, who comes with the boxes to take the cats and neuter them... etc etc etc..!!

Angelwings
If the grass is greener on the other side, its sure the water bill is higher !