A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 53:1Upon Mahalath--(See on Psa 88:1, title). Why this repetition of the fourteenth Psalm is given we do not know. (Psa 53:1-6)
with few verbal changes, correspond with Psa 14:1-4.
psa 53:5Instead of assurances of God's presence with the pious, and a complaint of the wicked, Psa 14:5-6 portrays the ruin of the latter, whose "bones" even "are scattered" (compare Psa 141:7), and who are put to shame as contemptuously rejected of God.