Can we have two main functions in an application engine? OR Can we have two sections in application engine with same name?

The answer is YES.

The section name is stored with the combination of the Name, Market, Platform and effective date.

Eg : Main.GBL.0.1900-01-01

From the above eg if we change any of the parameter we can save it with same name (name like Section01)

Possible cases are Section01.GBR.0.19-01-01 and Section01.USA.0.1900-01-01 is a valid case and will not throw any error. Here the difference is in the market.

If all the parameters in the name are same we will get the error like :

The fun in this is we can write a single application engine which can work in different market. From main you have a call section and you want the same application engine to work different for different market. In this case you will call the same section but based on the market the call will be handled to the respective sections. 

The above eg shows a single application engine with 2 Main functions but the markets are different.