Are you publishing to PDF? In Acrobat, when you duplicate a checkbox and if you don't change the name, this happens automatically. When I tested this in InDesign CC 2015, and exported to an interactive PDF my two checkboxes called Task1 were renamed Task11 and Task12—so it didn't work and this must be what you are experiencing? There may be another workaround, but worst case is to just set up the first buttons in InDesign, and then wait to duplicate them in Acrobat so that turning one on in one location turns the other one at the same time.
Thanks for the reply BarbBinder. That's exactly what I'm experiencing, but last year I was able to accomplish this directly inside InDesign. I don't believe I did anything special to the checkboxes besides naming them the same (i.e. - CHK-01 and CHK-01). I understand I can go through Acrobat, but this guide will have so many updates that it will become a hassle to go back and forth between 2 programs to get this to work.
Hopefully I can get this to work soon since my deadline is Tuesday!
I totally agree that doing it in Acrobat would be a undesirable workflow. I even found that Acrobat wouldn't let me rename one using an existing name—the only workaround I found was to duplicate the button. I'm fearful that this may be a feature and not a bug—I know from years of teaching forms in Acrobat that my students struggle with the opposite issue. They inadvertently use the same names and are baffled by the results. This won't help you in time for your deadline, but you might want to let Adobe know how you feel about the update: Feature Request/Bug Report Form .
Best of luck to you, Boywundr!