Converting Entire Score to Half-Time from 4/4

Not sure about my terminology here but I created a piano score in 4/4 time, by ear. Then I found out that my fellow woodwind musicians had all created their scores in 2/4 time so that, where I had used crotchets, they had used quavers, etc. Short of re-notating my score (note by note) to match theirs, is there any easier way to do the note-value conversion, such as there would be if I wanted to transpose to another key? Thank you! Sorry I didn't look before I leapt...