I haven't spliced the other end yet. In my use, I don't see value in splicing both ends. If I use a rope so long that the splice needs replacing, then that line is ready to be replaced. On the rare occasion that I am double crotching, it only takes a second or two to tie a good knot (gasp!).
That being said, I'd splice one end, climb on it for a week, then cut off the excess cover, then splice the other end.
The way we use rope, I urge against the double splicing. We literally will sit at the top of a 75' tree, then to get down, we will tie a friction hitch to the rope, then descend pushing 150' through that hitch. Even if the rope is very balanced, you are still introducing a bit of slack into the splice. That thought scares me. If we were splicing both ends and pulling just on both ends...well, there's no harm in that, but we tree guys (and gals) can't just leave well enough alone!
FWIW!
love
nick