Ўқиш китоби : эски ўзбек ёзуви намуналари, олий ўқув юртлари тил ва адабиёт факультеті студентлари учун кўлланма / тузувчилар: Т. Чермуҳамедов, Ф. Абдуллаев, П. Халилов.(OCLC #932769588)
This volume contains two books bound back-to-back, but as one is in Uzbek (which reads left-to-right) and the other is in Arabic (which reads right-to-left), they each get to have their front cover.
I’ve described this as dos-à-dos binding (“back-to-back”) in a note, which may not be precise, as such books typically have alphabets that read the same direction, so require a third board as a shared back-cover between them, and end up with more of a Z shape.
In structure, this is also similar to a tête-bêche binding (“head-to-tail”), which has two front covers, but has one volume flipped 180 degrees to accomplish this. As these two books really are back-to-back (and because tête-bêche binding is sometimes also called “dos-à-dos”), that term seemed more accurate/clear:
500 __ ǂa Dos-a-dos.