The canned puree will be sterile, so the concern about having to wait until secondary to have the alcohol to help sanitize is a moot point.
To my mind, the tradeoff with adding late in primary or as part of secondary is really if there is enough yeast in secondary to consume the sugars in the fruit and clean up by-products from the primary ferment. When adding to secondary the fruit will stress what little yeast there is, producing esters. In a dubbel this might be desirable, but can be avoided if you deliberately rack some of the yeast into secondary. Alternatively, pitching the fruit halfway through primary, say after a week, will also be fine.
Personally, I'd go with adding it towards the end of primary, skipping secondary and going straight to bottle or keg to keep in all that aroma.