prakrit realization in Grantham

[Whitney Cox]

While transcribing some Grantha-script MSS of Mahe"svaraananda's
Mahaarthama~njarii (in which the muula-text consists of gaathaa-s in
Maahaaraa.s.trii Prakrit, with a chaayaa and autocommentary in Sanskrit), I've
come across some seeming anomalies in the way the Prakrit text is written.  In
addition to the relatively large circles which follow the ak.sara and usually
represent anusvaara in Grantha (and as is this particular scribe's practice in
writing Sanskrit), there are rather small circles written immediately above
the ak.sara.  Strangely, however, the large circles seem in the Prakrit to
indicate gemination of the following consonant, while the small, superscribed
circle represents nasalization.  This conclusion arises from comparing the ms.
to the edition of Vrajavallabha Dvivedi (who reproduces the text of Ganapati
Shastri).  Is this sort of a practice (i.e. two different, language-dependent
ways of realizing anusvaara in the same text, realizing gemination through
what is usually used for anusvaara) something one sees in Grantha or in other
scripts?  Or, rather, should it be treated as two different ways of realizing
anusvaara, and should the ms. be treated as a text with a very different,
nasal-heavy, transmission of the Prakrit muula?  Any help would be appreciated,

Whitney Cox