While doing a search of GRETIL  I noticed that the following verse is a Maṅgala verse in six different purāṇas.  As far as I could see the rest of the  Maṅgalam was different in each purāṇa.  Do any list members know why this verse should be so popular as a maṅgala verse in purāṇas.

oṃ nārāyaṇaṃ namaskṛtya naraṃ caiva narottamam  /
devīṃ sarasvatīṃ caiva tato jayamudīrayet  //

is a maṅgala verse in these purāṇas:
garuḍa-purāṇaṃ
kūrma-purāṇam
mārkaṇḍeyapurāṇam
viṣṇu-purāṇaṃ
vāmana-purāṇam
bhaviṣya-purāṇam

Thanks,

Harry Spier