The Genesis 2:7 thing is taken out of context: "breath of lives"..."living soul." Adam didn't have multiple lives; the breath allowed (and allows) multiple lives to come forth through reproduction; he was only one living soul. "Plural deaths" in Genesis 2:17 ("muth-tamoth") is listed as singular in BW.
The same ideas hold in 53:8-9--"land of the lives," as you would translate it, does not refer to multiple lives in each person, but to the aggregate of individual lives in the land; and, again, verse nine's "bemotayw" is singular in BW.
If I've got any facts backwards, somebody let me know. However, this whole thing smells like week-old tuna.