I found this reply from VirtualBox users:
https://forums.virtualbox.org/viewtopic.php?f=8&t=74118
xactly. And we can do absolutely nothing about it. BlueStacks uses VirtualBox code without any attempt to coordinate with Oracle (which they certainly are allowed to do under the terms of the GPL). It is unfortunate that they mess up existing VirtualBox installs.
It is generally not possible to have two different VirtualBox versions installed on a system, unfortunately that is what BlueStacks effectively does. If this is a problem for you, please contact BlueStacks as Oracle has no relationship with them.