Mary McCabe appears to have two entries but the second one is a continuation entry; this just means an extra line had to be created because there was no space left on the original line. Not entirely surprising in this case because there were plainly a lot of notes made on this lady! 'See page 22 Bk II' is a reference to this continuation entry. Continuation entries were usually on blank pages at the back of the transcript book, but in the case of a large district that extends into a second (or very occasionally a third) book, the continuation entries will be on the back pages of the second (or third) book. This continuation entry is at the back of the second book, and also has a cross-reference to the original entry, which is only partly visible because the line below is blacked out.
Normally where there is a continuation entry you will only get a single result, and the image will link to the continuation entry. It didn't happen here, possibly because there is a discrepancy in the transcription (Marie in the first, Maries in the second). I have seen a few other examples of this, sometimes where there is a transcription error, but also where the clerk made a mistake writing the continuation entry, or where part of an entry is obscured by an ink-blot or discoloured sticky tape. So there is no linkage, but you can see from the piece numbers and the enumeration district code that this district, FDUF, extended into a second book.
There is no available list of what the various codes and abbreviations mean, but a date will be the date when the register was updated, not the date of an event itself. NR or CR followed by a number is almost certainly the serial number of the form used to notify a change, NR being 'National Register' (while National Registration was still in force) and later CR 'Central Register' when it became the Central Register of the NHS.
