CBE used to be a junction for a while. IR just didn't change the name.
1) Initially Podanur was the only junction in the area (Irugur-CBE line was not constructed until 1953 and there was no Coimbatore North station at that time).
2) In 1939, a bypass was constructed at PTJ so that trains going to CBE from MAS could avoid a reversal. This was known as the 'Nanjundapuram' bypass. It was abandoned around 1953, but the alignment is still visible today.
When...
more... this bypass came up, CBE became a junction.
3) In 1941, the PTJ-CBE MG section was opened. Dual gauge stations which are passing stations on one gauge and terminus stations on one gauge are also termed as junctions. So, even though the Nanjundapuram bypass was closed after a while, CBE remained a junction. It was the junction point for the PTJ-MTP BG route and the PTJ-CBE MG route.
4) When the Irugur-CBE line was opened, the junction point near Coimbatore North was controlled from CBE. In IR, usually the station which controls the signalling and points where lines meet, is called a junction (This is why many suburban stations in Bombay, Madras are not called junctions even though multiple lines merge there).
5) After the GC of the PTJ-CBE MG line and opening of the Coimbatore North station, CBE ceased being a junction. But the name was not changed.