Image degradation.. Convert Images..Jpg to jpg

[bslanger]

In the workflow I have, I make two sets of jpgs from the DNGS, one at 3150 pixels wide for upload to Pictage, and a second set
at 1550 pixels wide for proof prints.  The higher rez files are what I use for the Derivatives catalog.  So I am essentially making
a jpg from a jpg when I make the smaller pixel version from the Derivatives which are all ready jpgs.   Is there some degradation in this process? 
I cannot make Two sets of jpgs from the DNGs, one larger, and one smaller, because I re-order the files once they are in the
Derivatives, and then re-name.   I can change the compression settings, but I do wonder about the quality in this process.
I guess I should test it out, but thinking out loud here.

Brian

[Dierk]

Principally you have a loss. The question is: Is it visible, that is, does it bear on your results?