You are probably better at knowing your abilities than a bunch of us random people on the internet. However, a few thoughts:
1. For someone who has confidence: "I know I can get 100 miles in", it doesn't seem that out of line to do the same after one or two rest days. At times when I've pushed myself on consecutive days, the third day often seemed toughest. The first would be easiest, but even the second wasn't too tough.
2. Your exact abilities will vary by age, fitness and other factors. I've found as I've gotten older, my speed hasn't slowed much but the total amount of time I'm happy on the road has reduced. 35 years ago, my idea of fun touring was going from dawn to dusk including multiple days in a row. Now, I still enjoy getting on the road early, but if I'm done in early afternoon, that works well. In both instances, I was cycling at a rate that I could sustain for repeated days - but throwing a lot more time at it obviously meant longer distances.
My 35-year younger self did a trip once where I traveled 1194 miles in 9 days but one of them was a rest day. The other 8 were all 100+ miles, some by quite a bit. So it wouldn't have been a big deal then...
Now I can still do a trip where I travel 100+ miles in a day if needed. However, it means making a long day, and particularly a longer day than my norm of finishing in early afternoon (*). So it takes some more pushing than average and doing two of those days not too far apart then also becomes a bigger deal.
(*) Even my 35-year younger self would be on the road past early afternoon for a 100 mile day, but they were all long days.
3. So I think you'll be in best position to evaluate how much is really involved for you to do the first of those 100 mile days...and thus also whether two of them is a particular concern.