Here’s something you can do with your backup distance glasses: you can get stick-on removable bifocal lenses (little half-moons that you stick onto your glasses) for very cheap. This is one type, but there are lots of places that sell them. I got by with them for a long time before I found new frames I liked.
Another thing to do with the last pair of glasses since your distance 'scrip didn’t change much, is to have them tinted for sunglasses. Wally World just charged me $20 to do mine. No more fumbling with clip ons. 
Well, for one thing even with the highest index/thinnest lenses my lens are too thick for clips ons. I expect someone to come here and express doubt about that, but nonetheless it is true.
I am not tinting my backup lenses because if ever I DO need them I’ll need them for the week or so it will take to get new lenses for my main pair, and sunglasses are impractical for things like driving at night or being indoors, which will be required in such a case.
I use completely dorky “solar shields” that fit entirely over my prescription lenses. They also have the virtue of providing protection to my expensive lenses. I though a pair of those a year - at the end of that time they are so scratched and marred as to be useless.
Indoors on the job I wear safety goggles when appropriate - yes, over my glasses. Dorky as hell, but again, it protects the expensive lenses as well as my eyes.
As always, though, your mileage may vary and I’m sure someone else will be able to use the tip.
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How is Wal-Mart vision center? I shudder to think I may be going to Wal-Mart for this, but if I can get a competent exam and the new lenses I need there I’ll grit my teeth and do it.
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I still have my high-qualify titanium frames that I still very much like. Are these places willing to put new lenses in frames I provide?
I have always used Walmart Vision Center. They tend to have the lowest prices, i am a very broke college student, and i cannot legally drive with out corrective lenses. So i look for the cheapest, yet, most favorable, glasses. Walmart has never let me down. I am actually headed in tommorrow to get some new glasses, it is almost as expensive to get a new frame all together than to get new lenses in your old glassses, so i just get new glasses every time. But hey the prices aren’t bad at all. I’m looking forward to purchesing with Walmart Vision Center.
Since this thread is long over and done with, I’m closing it.