Your comments

Hello. I stumbled on the same workaround you did, Ronit. I actually deleted (unsubscribed from) the old calendar and no longer have duplicates. I would have preferred not to lose previous years' entries but I realized that if I really needed to look up past years' Jewish calendar dates this is easily-available public information so I gave up on having the info in my calendar. (And I discovered that the US Holiday calendar includes some of the big-deal Jewish holidays like Rosh Hashanah,  so some of the info is still available on the calendar for past years.)

Does anyone from Hebcal respond to these questions? I would think there would be a more satisfactory solution. I think that if it were easier to configure the years associated with each calendar, this would solve the problem. Hebcal lets you specify which Jewish years a calendar is for - however, I found that I still ended up with overlapping results.