There is identity between the numeral and the indefinite article at the segmental level for many speakers, with the distinction being a suprasegmental one, with the numeral receiving prominence, and the indefinite article being non-prominent. For other speakers, however, there is also a segmental difference, with the numeral being /waan/ and the indefinite article /wan/.
Source: Rickford 1987: 130, line 217
Source: Rickford 1987: 149, lines 365-366