i think you just have to open each datasource in the web client and review it to see if it is using ORAOLEDB.Oracle, or ORAOLEDB.Oracle.1 right? how many unique shared data sources do you have?
on my server, i only have six, so it wouldn't take too long to manually open each one to review.
i just tried to convert the originalConnectionString in ReportServe.dbo.DataSource to a string to charindex it, but it doesn't convert cleanly;
select
convert(varchar(max),convert(varbinary(max),OriginalConnectionString) ) As cn, *
from DataSource
Lowell