building help index with Texinfo 5 vs Texinfo 4

I built the help index using Texinfo 5.1 + build_index.pl and there
weren't any errors, but there is an off-by-one problem. If foo, bar, and
baz are functions or variables, then trying to look at bar fetches foo
instead, and baz fetches bar instead. (Not sure what foo fetches.) Has
anyone else observed that?

Also, for functions which have different argument schemes (i.e. @deffn
followed by @deffnx) there is supposed to be only one indexed item (the
first one). With Texinfo 5, I see an item for each @deffnx. Do you see
that too?

It seems likely that the output from Texinfo 5 is subtly different and
that's confusing to build_index.pl. How does the Lisp documentation
parser fare with Texinfo 5 output?

best

Robert Dodier