There are many reason the same employer would have a new EIN number.
It could be for any reasons as varied as new ownership, new location or new corporate structure.
With the changes to the tax laws, many companies changed their corporate structure this year. By changing their structure, their EIN would be changed.
What is important to you is that you enter your W2 information as it appears on the form you received. These forms are also directly reported to the IRS, so you need to match.