To get full advantage of the Welcome Back offer, you definitely need 2 PSN accounts, preferably from different regions, that would have had to be active before the outage.
Don't forget the Welcome Back offer also includes a PSN Movie weekend. The "ON US" Movie weekend is going on now, and it seems to have different movies in each region. Canada has Click, Hitch, and Underworld:Evolution. US accounts are getting Ghostbusters, Final Fantasy: Spirits Within, and Bad Boys. UK gets Final Fantasy, Resident Evil: Degeneration, and House of the Dead 2, with other movies being offered in other countries. These movies are rentals, and can be watched anytime within 30 days from time of download, or 48 hours from start of playback.
Also, take advantage of the free PS+ offer. You can keep the free themes, avatars, and wallpapers. You also get free games for 30 days (length of the PS+), 60 minute game trials, and discounts on others.
As well, the WB offer gives you 100 free items, a couple personal spaces, and a game for PS Home, if you use the service. If you have a PSN account from outside Canada, you can also get Qriocity music service free for a month.