The "Pig Tailing" will happen if the legs are twisted to tightly or if slack is allowed in it when hanging to furl (letting the weight bounce will do it).

I no longer hang Fluoro or Mono leaders to furl. I have a snap swivel mounted on the end of a piece off dowel. Hook a paper clip in the tippet end of the leader legs. Keeping tension on the legs lift them off the peg, the leader will furl as you relax tension. A few gentle pull and relax motions will finish it. A top of the line swivel and a drop or 2 of oil help.

I have been using this method for a couple of years after losing too many leaders to the bouncing weight!!