First, tell your doctor what you're experiencing since going off Dexilant.
YES, it's perfectly safe to take 20mg Prilosec (omeprazole) 2 times a day, especially since you've already run it by your doctor. I'd take one when you get up and one about 7 to 8 hours later. Always take it on an empty stomach and at least one hour before you eat. Give it time to kick in before you put food in your stomach. You said you "read the box". Are you taking Prilosec over the counter? If so, I would say taking two a day makes perfect sense. Over the counter medications are rarely as strong as the prescription form is. Unfortunately insurance companies will argue that but then we all know how they hate paying out when they're getting so much coming in. Can you tell I've had to go a few rounds with insurance companies in my lifetime???
I've had GERD for over 20 years, among other things, and I've tried every proton pump inhibitor (PPI) on the market and Nexium 40mg 2xday is the only one that works for me. We all get the joy of try this and try that before we finally strike it rich with the right medication!
If I didn't have humor to help fight the disease, I'd spend the rest of my life in tears.