wolfetho:
The wording of your question is most interesting.
It sounds as if you already have a second string sample collection and want to use it-- or you've tried to use it and are not getting the results you want.
Are either of the above statements true?
I've used VI in combination with other collections, and I've often found it better not to match every articulation so literally, depending upon the needs of the music. I'll play the part in as closely as possible, but a certain lack of "perfection" can add an element of realism. I like minor "discrepancies" and "happy accidents". Real string sections don't always play "together", and those players sitting further away tend to sound late in the real world.
I use VI as my front end strings-- those players sitting closest to the conductor, for example. I'll consider the "other" string samples as those players sitting further back in the section. I'll use Altiverb's predelays to place the two string sections "near" and "far" for more depth.
Most importantly, the pan fields of each similar section must match. If you've narrowed the 1st violins from VI to 30 degrees and panned it to the left, you want to also take the 1st violins from the other strings section, narrow it 30 degrees width to match VI, and then pan it to the same place in the mix as the VI strings. Same for all the sections, otherwise the strings will bounce around the mix and create undesired mix results.
That's what I do fo adding depth and adding a different color, but not soley for adding a second violin section because two sample collections are too different to be convincing spearately.
I like J's suggestion of duplicating and transposing the track, compensating with the mod wheel to trigger different samples. Two problems can occur with this technique:
1. In cases where an open string sound is desired, ie: low G on the violin, such notes can be noticeable when transposed. A change of patch/sample on those notes in the new track can remedy this.
2. Attention must be given to instrument ranges when bottom extremes are reached. Tranposing down can result in missing notes. This can be remedied by always transposing upwards. Higher limits of stringed instruments are more difficult to discern.
But the texture and color of tranposing VI remains consistent under the best circumstances, and under the worst circumstances this technique adds nothing to the texture or color-- if this is what is desired.
Personally, I would actually just play the part in again whether I used VI or another collection for those "happy accidents".
So, consider your specific reasons for wanting a fatter section and then determine which approach would best serve the results you desire.