I have somehow two accounts with my ID for stats.stackexchange.com The account linked with Stackoverflow has reputation of 1 while that connected with crossvalidated has rep (31+2B).
If you are saying that you have an account on Stack Overflow, and one on Cross Validated (stats.stackexchange.com), that is normal, as for each Stack Exchange site you have a different account; they are all associated, but they are all different accounts.
If you are saying that on Cross Validated you have two accounts, then you can ask a moderator of that site to merge your accounts: Find one of the posts you created with one of the accounts, click on the flag link, and enter the reason you are flagging.
If you don't have any post created with both the accounts, then create a question on meta.stats.stackexchange.com, reporting the links for both your accounts.
When two accounts are merged, the reputation is passed from one account to the other one.
The only reputation that is not passed through the accounts is the reputation gained from up-votes given with an account to the other account, or gained from answered given from an account and accented from the other account. So, if you used account A to up-vote a post made from account B, and those accounts are merged, the reputation for that up-vote is removed.
Now that you gave more information to find the other account, I can explain you what happened. The other account is an unregistered account.
This means you answered a question, or asked a question without to first log in, or create an account. The unregistered account depends from cookies saved in the browser you used to post; another computer, or another browser, doesn't have those cookies, and you would not be logged in automatically.
The day after creating that account, you register on Cross Validated an account.
Keep in mind that moderators merge the accounts if they have enough information to think both the accounts are created from the same user. There is nothing that block another person from creating an account with a username that is already used. In my case, there could be somebody else who uses kiamlaluno as username, and that account would not be merged with mine, even if I were to ask it.
In your case, looking the avatars used from the accounts, I would guess the email addresses used for the accounts are different. (If the email addresses were the same, also the avatar would be the same.) In such cases, it's probably better to email the Stack Exchange staff, using the email address linked on any Stack Exchange site's footer, under "contact us."