Does anyone use custom transaction records? Starting around time of 2018.1 upgrade, searches on custom transaction records intermittently return doubled values. At first it was only occurring via script (a script that ran a search on the record type would sometimes return a doubled value, sometimes return a single value), but yesterday I noticed that if I refresh a saved search a bunch of times, it would ~half the time display doubled lines. (there would be a second line with all the same info, same internal ID).

if you don't define the "Main Line" criteria in your search result will have duplicate lines, if you only want main line (header) the select yes, no for all the other transaction lines minus main line and either for all lines (which is default)

main line has been True on all the searches in question. And even so, it wouldn't explain why it would switch back and forth between duplicated and not duplicated just from refreshing...