All authors who had an existing HubPages account and had content transferred from Squidoo will have two accounts.
As you have observed, you have different login information for each of these accounts (email, password, etc.).
We strongly considered allowing accounts to be merged, but after looking at the whole technical picture we decided against it. If you only have a Lens or two it may not be such a big deal. However, for people with substantial traffic, we felt migrating them to their own brand new subdomain gave them the best opportunity to carry over their traffic with 301 redirects. This also helps avoid any confusion in regard to impacts on their existing HubPages traffic.
Accounts cannot be merged and manually moving your content is problematic for several reasons.
1. It is likely to show as duplicate because the original publish date from Squidoo only exists for the automatically transferred content.
2. It could have negative search engine results on your old account.
3. The content will not be subject to the Squidoo grace period.
Please make sure to not manually move your content to your old account if your would like to avoid the problems described.
You can find more about the Squidoo transfer process here.