Why the extra label on Dogfish Head specialty beers?

Most national beer brands attach two labels to their bottles -- one on the largest part of the bottle and another on the neck. Small breweries tend to just use one label because the added cost of the second label (materials, machinery, and the complexity of alignment) isn’t worth it to them.

It’s interesting to see that Dogfish Head usually follows this rule, but doesn’t for certain beers. The Dogfish Head 60-minute IPA is their flagship product. It’s 5% alcohol, sold in 6-packs, and has a single label. Their 90-minute IPA is also very popular, but is 9% alcohol. It’s sold in 4-packs for around the same price and has two labels. Why the extra label?

At first I thought it was to prevent people from sneaking the 90-minute IPA bottles into a 60-minute 6-pack, but now that I look at it, they have different color caps as well. So, why does Dogfish Head have that extra label?