Soon you will be able to use your WhatsApp account on four devices simultaneously. A screenshot has been shared on Twitter, which gives a glimpse of this new feature. However this feature is still being developed and is yet to be released for beta testing. Multi-device support on WhatsApp has been rumored for some time. A proof of activating a WhatsApp account on multiple devices has also been seen on the beta version recently.
According to a tweet posted by WhatsApp Beta tracker
Currently, WhatsApp does not allow users to connect the same account to multiple devices simultaneously. Apart from this, the application also does not support two WhatsApp accounts on one device. However, some Android phones have dual app support to enable access to the two apps.
WABetaInfo has clearly stated that the new feature is still being developed. This means that it is not part of any recent beta version and is probably limited to an internal test.