Lonan baptisms are also fouled up by the IGI - I checked a few years + hope to complete some more on Monday at museum - basically it appears that the original parish reg from which the 1911 official transcript was taken was unreadable in sections and thus the name of the child is missing - true to form the IGI has replaced some of these 1911 entries with 'patron submitted' (in fact I think some of thse are corrections (to date etc) but others are family reconstructions) - some of these family reconstructions have been incorrectly transcribed (you can see date of one child confused with another) thus you get two children in igi at same date; then someone had a look at the filmed versions of the Bishop's transcripts (apparently Janet Narisham did a list for the IoMFHS some years ago) and added a few other families (again patron submitted) that give the christian name as found in the BT. There is also one set of patron submitted family entries that appears totally fictious as I can't find any corresponding names in the BT.
The BT's I refer to have only recently been moved to the Manx Museum from the Diocesan Registry - most of the names in these BT's are not found in the IGI though one family does, so looks as if someone has consulted them earlier. They may help to clear up some of the mess that is Lonan registers but some years are still missing. There are 83 such marriages I have found and will post by monday.
I was given special access as the records are fragile and will not stand that much handling (they need to be microfilmed) - I will post, freely, on my site those records I have checked