When the following LaTeX code is processed by pdflatex, the resulting PDF file is the one attached to this message as "NoToBoth.pdf". The label is surrounded by a single pair of braces.

When either one of the commented lines is uncommented, the resulting PDF file is essentially the same as before.

However, when both these lines are uncommented, the resulting PDF file is the one attached to this message as "YesToBoth.pdf". The label is surrounded by two pairs of braces. This is undesirable.

A possible implementation of a solution was suggested in the following post:https://tex.stackexchange.com/a/585056/21685 It consists in adding the following three lines of code after the \usepackage{showlabels} directive.

\makeatletter \def\SL@eqntext#1{\rlap{\quad{\showlabelsetlabel{\SL@prlabelname{#1}}}}} \makeatother