Training 2x/day doesn’t really allow greatly more total volume, either total or for any given thing, during the week. Somewhat more is acceptable, but nothing like twice. Given equal comparisons: of course, twice what would otherwise be a small amount may be fine.
When going to a 2x/day program, I basically take what would be a good 1x/day program, divide it among the two parts, and add a modest amount to each half if necessarily even adding anything.
Absolutely, the same bodypart or same exercise can be trained in each session.
Ordinarily 30 sets of one exercise in one day would be too much. However, as to how high you could go in the situation you describe, a “set is not a set,” in other words some don’t come at as much cost as others, and I don’t at all think that 15 sets of an exercise in EDT comes at the same cost of say 1 set of 15 exercises each performed maximally. Nothing like.
So in other words, one hasn’t already paid a cost of what 15 sets would in all or most cases be, having done what is technically 15 with the EDT. And thus more sets are still possible to do than from simply a full 15 from a reasonable total.
While I’m not saying that it’s quantitative, by illustration say 40 reps of one exercise might be done in EDT at a weight that 10 rep sets could be performed at (if enough rest.) It doesn’t match up with 15 sets which would be 150 reps. I’m not saying that these 40 EDT reps exactly match up with 4 “typical” sets, either; but the cost is somewhere in the middle, and absolutely not as high as other forms of 15 sets can be.
One can’t just judge by the grand total number of sets (not that you were saying one could.)
I’m not sure if you’re saying you want to do EDT with military presses twice per day? No knowledge on that on my part.
But if the question was, were “15 sets” EDT-style done in one workout, if the other had say another 5 sets of a differing kind of protocol, that wouldn’t necessarily be excessive. Nor would necessarily some amount modestly higher than that. Fifteen sets of most other protocols, though, on top of the EDT, all the same exercise, sounds excessive.