Theoretically

[Mojotgefish]

Right I don't know wether this is feasible or it's just a stupid idea, I have a muntons hazy IPA and a muntons West Coast IPA and since my fermzilla is 55 litres could I combine both kits and dry hops and if so which yeast or would you use both yeasts?

Also would it effect the strength?

 

[JohnSand]

You probably can combine them. I would use both yeasts if they're similar, in any case you need enough yeast to ferment a double batch. The hops in the two brews may not play well together, or may become muddled if they differ much. The strength should be an average of the two if you use enough water volume for both. Remember only to include boil off volume for one batch if you boil them together.

 

[MaxStout]

If one of the yeast strains has a higher attenuation rate than the other, the higher-attenuating strain will generally prevail as to your FG. For example, if strain A attenuates 70-75% and strain B attenuates 80-85%, your beer will likely attenuate in the 80-85% range. Strain A will stop and strain B will keep fermenting. Not necessarily a bad thing, though. Plus, your beer will probably look hazy, due to the hazy strain's low flocculation.

Nevertheless, combining the two kits should work well.