You might be from the Southern Appalachian area if you know that those two words are pronounced the same. In South Western Virginia growing up, we always pronounced these words the same. In fact, I think the only time we ever pronounced it "hollow" was in reference to something like Sleepy Hollow that we knew was pronounced that way. We just said it "holler" and we still continue to pronounce it that way to this day. Well, I do anyway.
My husband, who is a little more citified than I am although he grew up literally less than an hour away from me, calls it by its proper hollow pronunciation. The first time I took him driving in some of my home territory I told him about the "hollers" and he got a kick out of it. Especially when we drove past a place and I told him to read the road sign. "Bear Wallow Hallow," he pronounced with the proper idea of how it read. "Nope, you're wrong. That's Bear Woller Holler." If you were to pronounce it the correct way, people would instantly know you was not from around these parts.
Growing up, my dad's family came from Dante, VA. (I could write an entire separate post about the pronunciation of Dante. To make that short and simple: It was named after the name who founded the town. You pronounce it the way that you would say "Can't", although to locals we also pronounce that word "caint" so it doesn't help to clarify much now does it. Haha!) It's a small coal town in the heart of the Appalachian Mountains. This entire tiny town was built by the coal company many years ago. And the cool thing about this little town is that it is made up entirely of "hollers." It's still that way to this day, although the population is much smaller now.
It's nice to know that all of these years later that is something that hasn't changed and I hope it never does. It's another one of those fun little quirks that make my home unique. So I'm going to go "holler in the holler, y'all!"