Before shim metal was easily available (and for fussy grannies who liked to bleach their pegs
) they used to have a slight recess carved where the tops met, and this was tightly bound with willow bast string.
Do you mind the old tattie peelers ? the Lincolnshire type ? the ones with the wooden (latterly plastic) handles that were wrapped in string ? That's what they did with the clothes pegs too.
M