Hello Sam Hopi,
If the Federal EIN of the LLC and the fictitious name (DBA) are the same, it should be ok as the IRS matches on the EIN not the name. At the state level, many states do require a separate state EIN for reporting state payroll taxes.
Here's what the IRS says regarding EIN.
https://www.irs.gov/businesses/small-businesses-self-employed/do-you-need-a-new-ein
A single-member LLC is treated as a disregarded entity - (a sole proprietorship) as long as it remains single-member you do not need a new EIN if you change the name of the business. For Example: If you operate 5 single-member LLCs each performing different activities that require separate schedule Cs filed, you use the same EIN for all 5.
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