I believe that the the two deaths is one and the same at COBAR NSW 1906.
William McGuinness, 75 years, at Cobar, Ref# 972/1906
and
William McGUINNESS, Father Thomas, Mother Sarah J, at Cobar, Ref # 12201/1906.
From what I can make out if the right couple William and Mary, then the births of the children all over the back blocks of NSW give an indication of his doing work on properties or traveling as a supplier.
It may be worth getting a full transcription of the last DC as it may contain how long in the colony and from where he came.
Neil