The daiin

[Anton]

The affinity of daiin to line-start and line-end may be explained by that it is a word that is likely in the start and the end of the line, or that it is the beginning of a word that is likely in the start of the line AND at the same time it is the ending of a word which is likely in the end of the line.

Or some combination of that.

One ready example that I can imagine is the German "der" or "den". As an article, it would be frequent in the beginning of lines (when there's the beginning of a sentence). As a word ending, it would be not infrequent in the end of the lines, because the end of the line is, at the same time, the end of the word which stands in the end of the line. Many words end with "der", like "ander", and many verbs end with "den".

The "derder" duplication would be possible when the sentence ends with -der, and then another sentence immediately starts with the article "der". We discussed such possibilities in the "Sequential repetitions" thread (which is one of the oldest in the forum).