This is the Victorian book of erotica, not a work of fifteenth-century alliterative verse. The covers shown would seem to be added by users who have confused the two works.
Alternatively, those users may understand the difference very well but someone else has combined the works inaccurately...
The singletons that lack author and ISBN information in this list may the only exceptions, and may actually be copies of the fifteenth century alliterative verse. The existing "bundle" of 29 copies with no author/ISBN information was combined with the erotica before the current separating and re-combining took place (20-Feb-2009). Many editions can be distinguished by "The Pearl" (erotica) vs. "Pearl" (poetry) but this is not 100% reliable, and should be checked before combining or separating.

ISBNs for the Victorian book of erotica include:
0786706708
1562011014
1562014102
0345294564
0345289358
0345410041
158288000X
Others are easily identifiable by "erotica" in the subtitle. Books without ISBN or author possibly may be the work of fifteenth century alliterative verse.

ISBNs for the alliterative verse, which should not be combined here, include:

0198126751
0393091449
0882950037