a death in 1985 that has been registered twice,
with consecutive numbering.
A death index entry in 1985 will have the person's DOB and the Month of registration plus the usual volume and page references & District.
Each page had up to ten entries (if click on the page numbers on FreeBMD) entered chronologically by date/time of registration.
By consecutive numbering do you mean consecutive
Pages in the same District or do you have the actual certificates showing the entry number??
The name of the person and District etc would assist.
Edit: From 1984, the indexes are in annual instead of quarterly volumes but include the month of registration. image added