DefinitiveStampr:Many states have multiple post offices with the same name, occasionally in the same county, sometimes elsewhere. The policy of the USPOD was that no state could have two post offices with the same name at the same time, EVEN IF they were in different counties. They believed it would confuse the sorting and routing of the mail (and probably were correct).
Lots of possibilities. Consider the following....
Mr. AAAAA proposes a post office named AAAAA in county XXX, and is approved. Five years later, Mr. BBBBB is appointed postmaster and he wants the post office renamed BBBBB, so he applied for a name change and it is granted.
Now over in county YYY, someone wants a post office named AAAAA, so he applies and because there is already a post office called AAAAA, the Post Office Department tells him to submit an alternate name, and he chooses QQQQQ, and it is approved.
Later, he learns that there is no longer a post office with name AAAAA, so he proposes a new name change back to AAAAA, and is approved, and then QQQQQ becomes AAAAA.
Often, when one sees multiple instances of post office AAAAA in the same county, it means that there was a period where the community was not able to find a postmaster, and the post office was idle. It would often restart with the same name and new postmaster once one was approved.
Another possibility is that the physical location of the post office was moved within the county, and the postal historians might designate the two post offices distinctly so that others would understand there weas a change. You might see this is postal history state lists were a post office was indicated like
AAAAA(1) XXX County 1820-1840
AAAAA(2) XXX County 1841- 1901
Sometimes the same actual office would be shown in two adjacent counties during different time periods. This might mean it was physically moved, or it could mean that the county boundaries changed or a large county was split into two or more new counties, and that post office was located within the boundaries of a new county..
Most of these types of changes occurred in the 19th century. By 1900, the post office structure was pretty stable, and number of post offices on the decline because of Rural Free Delivery.
Your ancestor, DS Lavender, was
THE ONLY postmaster of Clear Creek, Morgan County, Tennessee, and that is the way to present it when writing up his biography or family history. It might be appropriate to mention that the "Clear Creek" post office name was used elsewhere in other counties in Tennessee at other times, but those post office had no relationship to your ancestor.
Occasionally, this created unusual post office names. In Texas, once upon a time, a Mr. Walker proposed a post office by the name of WALKER, but was turned down because we already had one post office called WALKER. So he reversed the letters in his name, and his post office name of REKLAW was approved.

