Jean, when dealing with IoM records you need to note the parish, and say which one when you ask for help so that people don't have to guess. - And also say where the records come from which you ask about.
I assume the burial is from Brian Lawson's website:
"MC CARTHY, Hugh 71 Bra 22 Jun 1881".
That entry comes from the Braddan burial register ("Bra") which has been transcribed by the IoM FHS. It is likely that someone reading the board will have a copy, and won't mind looking it up to see whether any other details were given at his burial. There may also be a M.I. for him in Braddan which you can ask about on this board.
Where was the second burial you saw recorded?

Brian's index has the burial date, not the death date, so if ordering his death cert you just need to tell this to the Registry. Alternatively you could order it on LDS film to view for yourself at a Family History Centre, for a small fee.
Deaths registered in the Districts of: Braddan and Marown 1878-1901 Foxdale 1881-1900 Ballaugh 1878-1901 Kirk Michael 1878-1900 FHL BRITISH Film 454970.
You may need to order two films: Deaths registered in the District of Douglas v. 1 1877-1883 v. 2 1883-1888 v. 3 1888-1889 FHL BRITISH Film 454968.

This is also how you view the will - on LDS film - which you would also have found on the index on Brian Lawson's website. The LDS film number is given there.

Sue