Ok this is a dumb question but here it goes....

In the third movement of Shostakovich`s First Symphony, there is a strange notation I am unsure of. It says that it is in Common Time (4/4). In one measure marked Piu Mosso, there are two dotted half notes with a slah through the stem and a 6 over each dotted half note. What does this mean? Should it be three quarter note triplets for each dotted half note in the span of 4 beats?