They're both Grp IIIs, although the Ultra probably has a better, and certainly different, additive package.
I wouldn't fret.
Another 3K on this ad hoc mix won't hurt anything.
There those here who blend intentionally and there are those who dump random mixes of whatever is left over in their beater cars for an oil change. I know of no documented evidence that mixing oils by brand or grade or both causes any problems at all.
Nobody has ever reported observed problems here from mixing oils across brands, grades, groups, or all of the above.