I think in cases where there are two large agencies that can be abbreviated to the same acronym people who work for those agencies tend to use names that don't

I think in cases where there are two large agencies that can be abbreviated to the same acronym people who work for those agencies tend to use names that don't lend themselves to that abbreviation. So in this case it's the Energy Dept and Education Dept rather than something that might be turned into the ambiguous DoE.