How are daily precipitation totals computed?
Typical synoptic (hourly) obs come in about 51 past the hour (sometimes a couple minutes off).  The other reports you're seeing are generally subops (SPECIs) which generally only report precip since the last ob given, but the total of which should always be reflected in the hourly.

So for 2136/2148/2149 timed obshour... you just use the 0.24 from 2149, and it should include the others in it (so skip the others that would lead to double-counting).

On the other hand, the 659 ob being smaller than the 651 ob makes sense... as 659 is in the NEW hour... so would be reflected in the 751 ob (which is indeed higher).

I didn't get a chance to look too closely, but looks like all of these are unfortunately altered forms of the data.  I believe typical full data should have METAR or SPECI in it to indicate which obs you want?

But no big deal, if you look back at the rawer-looking data you gave, looks like you can find which ones you want by looking for the ones with SLP reported right about the end.  Or, even better, just look for the 6**** fields right about the end, which are the 6 hour total precipitation.  Just add the four of those up, and you'll have the daily total.

If you're trying to accomplish all this in Excel, some formulas could be worked up to automatically take what you need from the day's data, or you could use a regex in any of the variety of online regex testers.  Or writing some sort of script could save a lot of time if you're downloading a lot of data.  But the rawer data is often safer and more easy to work with.

I think I used a page like this for more info back in the day when I had to do it.