I'm going to upgrade to the new NXT client version, NRS v.1.11.3.  I've read that you should delete the the original client before installing a new version (but not the blockchain file).

I've upgraded the NXT client on two occasions before without deleting anything. I found that when I installed the new client it seemed to simply write over the old files and everything to worked perfectly afterwards. Am I right in continuing to install the new client without deleting any files beforehand?