Nope, the same processing time must be used. Even for that, if the canned tomatoes don't contain added acid, you may also have to add that. Commercially processed tomatoes go above the home pressure canning heat. Add lime juice, lemon juice, or citric acid, or even cider vinegar. Keep in mind the tomatoes, if they were 'chunky', will now soften to a sauce. The reason is simple. Opening the can of tomatoes brings in room air, and anything else thats living in the house that is also airborn. Recently I posed a similar question about large cans of mushrooms, and wanted to fill smaller jars and just BWB them. I guess its not allowed either, unless I pressure canned in small jars.