Soc in so/sp
The so/sp seems to be driven by pure Soc, but unlike so/sx, it comes off as more awkward and bumbling when trying to interact with people. They're often self-conscious, and do anything they feel that might get them accepted in the group, even if it's questionable. They can socialize fine, but it is often on their own terms, e.g. if they feel as if their line has been crossed or are being taken for granted, they will back off or outright halt social activity with the person.
Soc in sp/so
The sp/so will use their Soc connection to a greater whole to provide a stable resource to support their Sp lifestyle. Though preferring to mind their own business, they will readily take on social responsibilities or situations if it doesn't intrude on their inner boundaries. Although Soc-second, this stacking tends to handle people better than so/sp, since their sp needs are established clearly, while so/sp is usually oblivious that they have sp inhibitions at all.