Vivaldi, that Eulenburg score is probably a reprint of the same Muzgiz score I just posted (Prolog and Act I). As far as I know, the only score ever issued before the Muzgiz was a lithograph of a copyist's manuscript issued jointly by Jurgenson and their German agent D. Rahter. It was prepared by a copyist in Hamburg and is in 2 volumes, 705 pages total. This score is extremely rare because only about 50 copies were ever printed. There are probably no more than 10 in existence today.
If you want to scan a few pages of the Eulenburg and post we can compare. It would be highly unusual for Eulenburg to have gone to the expense of engraving a 1000-page score fresh, but it is not completely impossible. Jurgenson engraved and printed a few excerpts from the ballet, plus the Suite, Op.66a which was made by Siloti after the composer's death.