The point is that the electors act as party representatives.
In the event of any shenanigans or voting irregularities the reps - who were honor bound but not duty bound could change their vote, being the ultimate representatives in a republic.
This was intentionally chosen as math was available back then and a total vote count for president could be achieved even back then. This was one last check and balance on power.
That’s why electors are traditionally party appointees and the process is intended as a formality.
That’s true - they can change their votes. So, you’re right, changing a vote is not the same as voting twice. Got it, I think. Thanks.