Here's what I'll actually do on my set of jib sheets though:

Buy them in a single length and use the proper knot in the middle.
(Good picture of it on the Wooden Boat Magazine Forum discussion of
this subject).

Then it's time to end for end the sheets, cut them and put the
eyesplices in the other ends. Then use this knot.

This all started because I bought a rope for a mainsheet, screwed up
my first attempt at an eyesplice, and then had enough for one jib
sheet but not a mainsheet.

--

Roger Long