We only enter double names like that- we have a lot of accounts being shared with non-same-last-name contacts. With both names in the first and last field, you’re able to search for either person without having to ask “Could it be under another name?”
We’ve had no CC issues- I don’t think the name field affects the card processing at all.
I think any potential confusion is worth the searchability. Though we did put in a request to tie two contacts together under one club membership. Maybe someday.
Too new to Vin65 to know what it affects but I sure like being able to have both names, especially in the first name field. Then our emails go to “Hi Tom and Sue,” and that seems a lot more personal.