Is it possible to convert regular pick-list to multi-select pick list?

Is it possible to convert regular pick-list to multi-select pick list?

I have a regular drop-down pick-list and we realized that we need this info as a multi-select pick-list.  I don't think there is a way to convert from one type to the other, but what is the simplest way of moving the data over?  Meaning, whatever value is currently selected the Contact's pick-list would also be selected in a multi-select pick-list.

Thanks in advance.