The compound word sub+eo seems to appear in two different forms, subeo and subeor. One is a normal indicative form, the other deponent. They appear to mean more or less the same thing. What is the relationship between these two forms? Should they be regarded as completely equivalent synonyms or is there some subtle difference between them?
Is there a evolutionary relationship between the two forms? In other words, is one form more prevalent than the other depending on the time period of use?
There are other words like this, such as polliceo and polliceor where the regular verb and deponent form seem to be exact synonyms.