Two ultras within 6 weeks?

I am slowly but surely starting to plan out my race schedule next year. I have previously run a 100km trail ultra and regularly run marathons/50kms as secondary races.

I’m eyeing a 135km race next year as my A race. Would it be a good idea to run a 100km “B race” 6 weeks prior? I could use that as my longest training effort for the A race and then use the time in between to keep the mileage moderate and rest up. I could alternatively run a 50km race instead.

Thoughts? Anyone run back to back 100km+ and find a good strategy to avoid injury?

Thanks!