Breen (1971) says that Dhidhani (G42) is given by Bulanu G12.1 and Waluwara G10 informants as a dialect of Bulanu. Documentation on Bularnu G12.1 may be relevant.
Breen (1988:1) says there are three dialects of the same language as Bularnu G12.1: Dhidhanu (G42), Baringkirri G51 and Indjiladji G52, cautioning that the variant form of the last, Indjilandji, is also the name of a neighbouring language to the north G14.
Brammal (1991:2) notes the existence of these near-identically named languages, but says he is doubtful that Injilaji G52 is actually distinct from Bularnu.
Barkly Downs (Breen 2008 p.c.). The map in Breen (MS 111) shows it as a northern dialect of Bulanu (G12.1).
Speaker numbers were measured differently across the censuses and various other sources listed in AUSTLANG. You are encouraged to refer to the sources.
Speaker numbers for ‘NILS 2004’ and ‘2005 estimate’ come from 'Table F.3: Numbers of speakers of Australian Indigenous languages (various surveys)' in 'Appendix F NILS endangerment and absolute number results' in McConvell, Marmion and McNicol 2005, pages 198-230 (PDF, 2.5MB).