The duplicate course credit rule is simple: you cannot complete the same course more than once for credit — ever, not just within a renewal period (16 TAC §73.25(e), §75.25(d), §83.25(e)). Take a course twice and the second completion earns nothing — your renewal would come up short on hours.
The detail that catches people: delivery format doesn't make a course different. If a provider offers the same course content online, in a classroom, and virtually, TDLR considers all of them the same course. Switching from the online version to the in-person version of identical content is still a duplicate.
What makes a course "different" is its content and its TDLR course approval — each approved course carries its own course number, and course approvals run one year at a time, so providers' offerings change across approval periods. Your TDLR CE history lists the course numbers you've been credited for; if you're unsure whether you already took a course this period, check your CE hours before enrolling.
The rule matters most for annually renewing electricians and ACR contractors, who are back for CE every year, and for cosmetology/barber dual license holders applying one course's credit to both licenses within a cycle.
What it means for your renewal
Vary your course each cycle and you'll never meet this rule in practice. If you renew annually, don't simply re-enroll in the identical course from last year — confirm the current offering is a different approved course, or pick a different provider or topic.