Same entry in other lexica, and cf. also Apollonius, Homeric Lexicon 59.12, which glosses the phrase di/ptuxa poih/santes (4 times in Homer, of the envelope of fat covering sacrified meats) with du/o peribola\s e)/xontes. On the adjective di/ptuxos see generally LSJ s.v. The lexicographers' diptuxi/a, the plural of a related neuter noun (overlooked in LSJ), came to mean (e.g.) diptychs and double writing-tablets.
See also Lampe s.v.
[1] Drachmann conjectured u(perbeblh=sqai "is laid on top." Theodoridis on Photius, Lexicon delta664, endorses Hesychius' e)pibeblh=sqai.