My personal guess is you will find some users have their Android devices plugged into their computer, and their Android device will be accessing the network via that computer - and that Meraki is correctly reporting this.
This is based on the HTTP GET from the client device as described in this document. You should obtain a packet capture to confirm that this information is correct. Also, some clients may misidentify themselves when specifying the user agent string field in the HTTP GET request, and enforcement of device type policies is done on a best effort basis depending on the information provided by the client. If you need to enforce security-focused policies based on device type, we recommend that you use a solution such as Meraki Systems Manager or Cisco ISE.
even when you have blocked android devices in meraki controller some devices access wifi. How??. cisco need to address all of these things immediately.