[PLUG] too many identical md5sums - is this normal?

[website reader]

In running md5sums against my files, I found in my home folder that 522
files had the same identical md5sum (of the 176K+ files) but when I did a
search, they were not the same files, in fact most are different from each
other.

Is this normal, that 522 different files give identical md5sums? I have
another set of files with 191 identical md5sums.

Or is something broken with Ubuntu 10.4  64-bit linux?

I am concerned now, as it was my belief that identical md5sums are hard to
duplicate (with different files)