You are confusing NeatHtml and NeatUpload.
NeatUpload 1.3.18 (the newest version of NeatUpload available) is included with mojoPortal 188.8.131.52, the file version is 1.3.3520.16252.
I'm really not sure about the error you are seeing. I have not encountered that error in relation to NeatUpload.
I wonder if you have a caching proxy server or some other thing about your environment that could be a factor.