Allow multitasking / overlapping intervals

I'm using taskwarrior with the timewarrior on-modify hook script. While compiling some software (one task), I worked on some other tasks. Taskwarrior lets you "start" multiple tasks at once, but timewarrior stops timing the first task when the second task starts. I'd like to be able to easily record and see how long the compilation took, as well as the other tasks accomplished concurrently. I tried modifying the interval in timewarrior, but it wouldn't let it overlap with another.