Alright! I found out that posting in Multiply automatically posts the entry to Blogger. However, the same is not true when I post first in Blogger. Apparently, I would have to import the blog post to Multiply first.
So I guess this leaves me safe to re-post my blog entries in Multiply to Blogger and as for the original post dates, if I don’t get a reply in the next 48 hours, I believe I would simply copy/paste them and attach the original post date to the beginning or end of the entry. But I do hope there is a faster way of doing things. This is technology after all.