If you updated your tax ID at any point during the year (by submitting a new W-9 in your dashboard), you may receive separate 1099s for payments before and after the new W-9 was submitted.
For example, if you formed an LLC and submitted a new W-9 with a new tax ID number on May 1, you may receive one 1099 for January–April payments and another 1099 for May–December payments.
If you have more than one site here and each has a different tax ID in the payment profile of your dashboard, you may also get more than one 1099.
Note: If you make a change that affects whether or not you are eligible to receive a 1099 (such as switching to Paypal for payments or changing your business structure to a corporation), then your 1099 will only reflect your payments for the part of the year during which you were eligible to receive a 1099. It is your responsibility to file taxes within the requirements set by law.