I personally throw them away, so I open them flat with pliers, and then twist them off and I have yet to damage a tie...
I put the needlenose pliers at 90 degrees to the rail, then turn the pliers along their axis.
The pliers push against the rail end, so no pressure on the tie..
the twisting action curves the now flattened joiner and that curving helps release the tab up and out as opposed to flat pulling it away.
No damaged ties, but again I toss the now flattened joiner.
Greg