Do I need?.........

Thumbs up for the advice re easy-peel stickers and/or a bit of bright coloured insulation tape.
Another good idea is to mix & match your skis with a mate and then leave one 'pair' a bit away from the other - that way you have 2 miss-matched pairs, which means someone else is less likely to confuse them with their own (or nick them!).

I actually swapped a ski with one of my mates once. One twintip park ski and one short carver. It made left turns very quickly and right turns a lot slower but the skis kept crossing into each other! We both had the same size boots and din settings so it worked well.

im liking the insulation tape idea! I feel a trip to the hardware store is in order!

Thanks