Code for finding repeated entries with different data
Your code uses several constructs that have a bit of smell in R.

Foremost is how you write the loop. An immediate replacement would be to replace the repeat with a for(i in seq_len(nrow(project))) (especially the hard coded 394 reeks)

Also you don't need to initialize the variables you will not use outside the loop - that will just prevent them from getting cleaned up after the loop.

A more R like way would be to use some higher level verbs that operate on the whole table. Such as provided by dplyr. Supposing you have something like an id in the lines you would write something like

left_join(project, project, on=c('HOUSE.NO')) %&gt;% filter(id.1&lt;id.2) 


such commands are usually easier to read and usually much faster than looping.