The 40A ESC now has a switching BEC but this is the spec from the 30A linear BEC....

This model features an advanced LINEAR BEC circuit able to provide 2A/5V to power your servos while running up to 4 cell Lipo packs.
2A is not mich.....

Also this note is on their web page....

NOTE: When connecting 2 or more LIGHTNING ESC’s with switch mode BEC’s together you MUST disable the BEC on one of the ESC’s. To disable the BEC you simply pull the red wire out of one of the servo leads then insulate it. Once you have done this, you may then connect the ESC’s together using a Y harness.

Failure to isolate all but one Switch mode BEC will damage one or both of the ESC’s. EXTREME RC is not responsible for damaged ESC’s that are wired incorrectly.