Encounter's "common timing library"

From all the documentation that I see, it looks like "common timing library" in encounter's "import design" menu should point to the typical case library. Similarly to how the "max" and "min" libraries point to the worst and best case libraries. 

However, when I look at the log, it says that its overwriting the libraries. See below. 

Reading max timing library <my_wc_timing_lib>

................etc

Reading min timing library <my_bc_timing_lib>

................etc

Reading max timing library <my_tc_timing_lib> 

................etc

Reading min timing library <my_tc_timing_lib> 

................etc

Those last two messages seem to indicate the reading in of the common-timing library is over-writing my max and min timing libraries. Is this correct? Is this what I should see? 

Thanks

Matt