You could probably just zip tie the twins and leave the others bare, if you don't need to distinguish among the others. If it were me, I would put the zip tie on the opposite leg for each of the twins so you can tell them apart.
I just did tiny zip ties on mine from this hatch for the first time. I want to track which ones grow up to look like what.
Nearly final count: two of six LF EEs hatched last night at end of day 21. With the one of three from the earlier part of the staggered hatch, that's a 33 percent hatch rate. - and that was with all local eggs. We'll leave the other four in the bator over the weekend, but I'm not expecting anything given I tapped and listened to all four remaining eggs when removing the live chicks.
We had a lot of trouble getting the incubator to maintain a steady temp this time around, so - silver lining - I was able to convince the rest of the family to buy me an early Xmas present, a Brinsea Maxi EX. It will be here in good time for the Nov. 21 OD eggs I have coming. We learned a lot with this hatch and I am hopeful we'll have much better results next time around.