I was somehow certain that it'll prioritize first package library sees in .libPaths(), but reading actual code it looks like your case will be handled by this:
if (length(paths) > 1L) {
if (verbose)
warning(gettextf("package %s found more than once, using the first from\n %s",
sQuote(pkg), paste(dQuote(paths), collapse = ",\n ")),
domain = NA)
paths <- paths[1L]
}
However, there is nothing specific mentioned in helpfile for library(), so maybe it's handled differently (code is a bit hard to parse just by looking at it).
So, my suggestion would be to try
. I'm now curious whether you'll get the warning above.