I have, same 2 guyst constantly. Work togheter flawlessly.
I beat some top double okw teams in last patch, when they were far far stronger, beating them in this patch is walk in the park.
Ml 20 is kind of harsh because some maps let the stuka hit it without any effort, such as crossing in the woods.
And ml 20 can shoot from base to base and kill his whole army on retreat. Besides, stuka does not always kills ml 20 in one barrage, and if OKW got stuka in the first place, it means you failed to press them hard enough.
If you looking for more specialized how-to-wreck double okw with least effort strat for soviets i personally recommend t2 from start, followed by 3 hmgs (on some maps in case of early rush you want script first double or triple (very rare case) hmgs to follow). It is your early game, just 3 squads in addition to starting engies. You should play aggressive, at this point okw does not have units which can stop you. Rush buildings, back cap with engies, cover maxims with each other, as soon as you have scripts which later should be replaced with maxims in buildings, its pretty much gg.
Than all depends on situation. You need for sure only two things: rushed quad and at gun. If you have double fuel control, you should skip at gun, build second engie and start building t3 as soon as you have 80 fuel, its very crucial (and, ofc, retreat your first engi to base prior to that (on 60 fuel or close) to help in construction). If you do not feel confident enough, go at gun than t3 (again, your starting engie should be at base exactly at 80 fuel tick). Than just build m5, upgrade quad asap, concentrate your forces around it and push hardcore, if you do not have double engies yet, build second engie in addition to your starting one, you need them for fast repair,
Now, again, everything is situational. If your enemy do not have at, and you feel you are in strong position and have solid lead, just attack him, push shrecks around, chase squads on retreat to kill them (quad can even decrew OKW base defenses without losing more than half of hp, and you can recrew them with engies supporting your quard, and from there on, its gg), build second quad for maximum destruction followed by at gun to cover quads.
If you are not in good position then you should blob your hmgs with at gun and quad behind (rebuild it if needed, you need reinforcements on the field), use engies to scout ahead (and one of them should be upgraded with sweeper, coz mines is only thing capable of killing quad in good hands). Turtle to OKW hq and start killing it with at gun (attack ground if needed). Even if two of OKW players come at you, at that point of the game you should be able to simply reinforce from quad on max distance, until they all dead/suppressed to death by your hmgs and quad, even if they have puma by some miracle, your at gun should kill/deter it. Thats point where game should be over, 8 or 9 minutes.
But if its not, you should pick terror doctrine and build one shock squad for flanking, start spamming su76s, build ml 20 at good position to fire at hqs/base asap, continue pushing OKW with maxims and at guns reinforced by your quad, and when you get kv-8 attack with it in front and su-76s behind, covered by at gun(s). Your su76s (by that time you should have 4 or 5 of them) should kill any tanks they face, and kv-8 sweep all infantry, use prop arty on blobs, hmg walls or rakketens to make life easier, follow mass retreats with ml20 hq/medhq bombardment.
ONLY thing which can stop those kind of pushes is pak 43, and pak 43 dies to 1 ml 20 barrage, so it should never be a problem.
If you lose with all of that, you were outplayed.
p.s. Stuka can kill ml20 in one barrage, but it is really rare.