Yeah, as Germania explained, Crunchyroll has separate videos for each audio tracks. One way to get around this is to subscribe to Crunchyroll through Amazon Prime Channels if you're already a Prime member, as they offer multiple audio tracks (you can link your Amazon account to Crunchyroll, that way you get access from both ends, but it must be Magafan tier, at least for the first month. After that you can downgrade to a lower tier and still retain the link).
Another way is download both videos from Crunchyroll then use MKVToolNix to repackage it into one video. This is almost effortless, when both audio tracks have the same length, but if they are of different lengths, you will need to find out the difference and make proper adjustments when remuxing (usually happens with older titles, especially ones that were transferred from Funimation, due to different opening logos)
