I never heard of double planting toms. Maybe I should do a search.

I hos planted my wsn tomatoes this spring (actually, haven't quite got them all in the ground yet). But I am planning to thin them down to the strongest plant after they put on some growth. I do vaguely remember talk of leaving them in clumps last year, but don't remember any follow up.

I found the link from last year.

Here is a link that might be useful: the link