Agreed, but I'd just assume avoid dual builds and targets at this point... a project I'm working on started with IE11 support and dual build targets, but broke

Agreed, but I'd just assume avoid dual builds and targets at this point... a project I'm working on started with IE11 support and dual build targets, but broke in IE11 about 3 weeks in, so changed the "legacy" build mode to a page noting the requirement for a modern and secure browser.