If mixing was such a big deal, then there would be engine failure when everyone changes oil brands every OCI and the remaining oil in the engine caused a problem... But there isn't.
You might lose some of the performance from the more stout LL01 0w40, but i doubt anyone is trying to push OCI barriers on a new vehicle anyways, the oil is likely to be dumped before it ever has any issues.
These oils are somewhat similar, although the 0w40 doesn't use magnesium like the high mileage oils do. 1 quart of the HM oil in 6 quart sump is 16.67% of the sump, which will hardly change the calcium/magnesium ppm enough to make any measurable difference. They are both the same level of moly and very similar ZDDP levels. The HM oils only use about 2/3 the level of Boron we typically see in M1 0w40 API SN, but i doubt that makes much of a difference either.
I think since you already have the 5 quart jugs, it would probably be easiest to dump 1 jug + 1 extra quart to get rid of it, and i am sure the engine will be fine.
Also mixing becomes even less of an issue the warmer the climate you are in, and since the OP isn't likely to be in South Dakota, that makes him even safer in his mix.
How much of the Mobil 1 HM 5w20 do you have ? Do you have enough to mix all that 0w40 up for awhile or will you need to seek another 20 grade oil to mix it with?