I am pretty sure it correctly selected 15.1 because this has all been worked out by the Operating System developers; probably either will work.  A definitive way would be to check the SHA sum but that is a lot of work.  Easiest way may be just to start up Cinelerra, use the Settings pulldown, pick the Preferences option, click on the About tab, and in the bottom left hand corner above the OK button, check the "built: May 31 2019 timestamp" and use that timestamp to see which one is the closest to the time of 15.0 at around 17:47 or 15.1 at around 22:34.  The builds do not get done in any order except the partition order on our disk build system here.  Leap 15.1 was newly installed so is on a later partition and thus built at a later timestamp.  Let me know if this works!  Phyllis