Metra normally just runs two units together rather than on each end of the train. If they had to, a loco could be put on each end of the train and MU'ed to run in sync by using the 27 pin cable that is used for the cab cars.
Though I haven’t heard of a bi-level train with a loco on each end happening on Metra anytime recently, it did happen at IRM with their bi-level commuter train a few years ago. The engineers’ brake valve on the cab car developed a problem rendering it inoperable for the rest of the day. It was an extremely hot day and the bi-level train was one of the very few places at the museum with working (well sort of working in this case) air conditioning available for visitors. So rather than pull the train out of service and leave the visitors with one less place to cool off, the stopgap solution was to take a second engine and couple it to the cab car end (though the locos weren’t MU’d, but the crews of the other trains didn’t know that….) and use the cab car just as a regular coach. So once underway with an F7 on one end and an E9 on the other end and only three bi-level cars; comments started coming over the radio from the other trains like “jeez do you guys think you have enough horsepower for that train???!!!!)