Running some simple examples, I noticed that there seem to be some differences between the output created by the commandline and what the UI create (on the exact same input assets).

I've attached a photo here noting the most obvious differences I've observed

I'm wondering if anyone might be able to shed some light on the why i might be seeing these differences and whether there is a way to address them do that the output from the commandline is faithful to the both the original and the version created by the union operation in the UI.

The path union operation from the UI is flawless, but not so from the command line so this was a very unexpected result.

Are these types of deviations common, or perhaps is this something that can be addressed with different settings/arguments.  

for reference, where command used:

./inkscape --file 'c:\users\user\dog.svg' --select 'top' --verb 'SelectionUnion' --export-plain-svg='c:\users\user\dog-plain.svg'

Run from a poweshell session on windows 8.1 with Inkscape 0.91 r13725 (Jan 30 2015)

The original (path, not text) 

A Comparison of the two 

​

Otherwise this seems to be a bug.

Interested to learn more,