As noted in the SBLHS 2 §§6.1.4.4, 6.2.15, multiple publishers should be separated by a semicolon in a bibliographic entry.

15. Birger Gerhardsson, Memory and Manuscript: Oral Tradition and Written Transmission in Rabbinic Judaism and Early Christianity, ASNU 22 (Lund: Gleerup; Copenhagen: Munksgaard, 1961).

Gerhardsson, Birger. Memory and Manuscript: Oral Tradition and Written Transmission in Rabbinic Judaism and Early Christianity. ASNU 22. Lund: Gleerup; Copenhagen: Munksgaard, 1961.

Note the correction to the order of the Gerhardsson’s first and last name in the bibliographic entry, per our post here.

A similar practice should be followed in bibliographies when citing a volume that is published simultaneously in multiple series.

Evans, Craig A., ed. Of Scribes and Sages: Early Jewish Interpretation and Transmission of Scripture. 2 vols. LSTS 50–51; SSEJC 9–10. Edinburgh: T&T Clark, 2004.

In footnotes, however, separate multiple series with a comma.

16. Craig A. Evans, ed. Of Scribes and Sages: Early Jewish Interpretation and Transmission of Scripture, 2 vols., LSTS 50–51, SSEJC 9–10 (Edinburgh: T&T Clark, 2004).

For more information on how to separate distinct publication elements in footnotes, see our post here.