Previously Kwat Kwat was incorporated into S40 (formerly 'Bangerang / Kwat Kwat / Waveroo'). However, very little is known about this name and sources vary as to its status as a language name and its identity with respect to other groups. Some sources have treated Kwat Kwat as a distinct language variety. Clark (1996) treats Kwart Kwart (S97) as a 'subdialect' of Waywurru S89, though in later publications he changes his position, linking it to Yorta Yorta D2. The nature of this link, however, is not clear. In Clark (2005) Kwart Kwart is termed a variant of Yorta Yorta, which could mean a dialect or an alternative name. Clark (2005) says his view is supported by Bowe and Morey (1999) but they say that Kwat Kwat is a 'sub-group of the Yorta Yorta/Bangerang macro-group' (p.5, fn. 7). Clark (2011) calls Kwart Kwart 'a cognate' of Yorta Yorta, but it is not clear if he means the names are cognate or the language varieties are related. Bowe (2002) admits the possibility that 'Kwat Kwat / Quart Quart / Quarta Quarta' may be a slight variation of the name 'Yorta Yorta', though she seems to lean towards it being a dialect rather than an alternative name.

All sources acknowledge the uncertainty of this name and many surveys omit it entirely (Dixon 2002, Oates and Oates 1970, Capell 1963). Bowe (2002:140) points out that, without language data, it is impossible to know 'whether Quart Quart "language" was a dialect, or a set of dialects, of the macro-language grouping Bangerang/Yorta Yorta, or a dialect of some other language, though the former seems to be the most likely.' Lloyd (1985:1) mentions the name 'Whroo' (referencing Andrews 1920) which he says is 'a group of the Kwat Kwat, a branch of the Bangerang', noting that Lake Moodemere was their gathering place. Andrews (1920:35) locates the Whroo at Wahgunyah, a couple of kilometres to the north of Lake Moodemere. While Whroo may appear to be a permutation of the name Waveroo/Waywurru (S89, but previously treated as part of S40 with the former reference name Bangerang / Kwat Kwat / Waveroo), and the location would fit, Eira (2016 p.c.) suggests that 'whroo' is simply cognate with 'wurru/wurrung' meaning 'mouth' or 'language', a common component of language names in Victoria, and thus likely a mistake. (Note that there is a place called Whroo, though it is over 80 kilometres to the south-west of Lake Moodemere.)

Robinson (in Clark 2003:160), the earliest source for Kwat Kwat, considered it a subgroup of Waveroo, but contemporary sources tentatively link it to Yorta Yorta D2 as either a subgroup (Hagen 1997), dialect (Bowe 2002) or alternative name (Clark 2011). Eira also notes (2016 p.c.) that she has studied the Pallanganmiddang records (identified by the contemporary Waywurru S89 community as Waywurru language) and they are not Yorta Yorta (D2) or Bangerang (S40). She suggests including Whroo as a possible alternative name for Kwat Kwat (S97) on the basis of Lloyd's description.