Here is an excerpt from the Speccy .txt snapshot file;
This also occurs when connecting another USB drive of a different make, the values from the HDD SMART are reported for the External HDD.
I have highlighted the start of the data for each drive. The partition sizes and structure is interpreted per drive but HW IDs and SMART table data is just duplicated. I have tried the portable builds and the result is the same on 32-bit and 64-bit versions of Speccy.