gm convert and image metadata

I am confused as to what metadata a command like

gm convert -geometry '1350x900>' -filter Lanczos -interlace Line
-unsharp 0x0.2+2.0 -quality 93 foo.tif foo.jpg

preserves.

My goal is twofold: to keep both the ICC color profile, and the
photography data such as aperture and shutter speed in foo.jpg.  If
there is a way to do that just using graphicsmagick alone, that would be
great, but using an external tool like exiv2 is fine too.  Here is a
sequence I tried:

exiv2  ex foo.tif
gm convert -geometry '1350x900>' -filter Lanczos -interlace Line
-unsharp 0x0.2+2.0 -quality 93 foo.tif foo.jpg
exiv2 in foo.jpg

After I do this I try

gm identify -verbose foo.jpg

and I see BOTH

Profile-color: 25884 bytes ;on the top level under Image

AND

Inter Color Profile:  ;under Profile-EXIF, much binary data follows

So, it seems I end up with 2 copies of the color profile.  Better than
none, I guess, but not perfect :-P

As I said I am confused.  In large part, I admit, because I have not
actually read all the alphabet soup standards (EXIF - and how does that
relate to Exiv?, IPTC, et cetera).

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