For some of your advertising campaigns you might see multiple clicks from the same IP addresses, which initially may be considered as bot traffic, but we recommend to check if they correspond to the "Google's Data Compression Proxy for Google Chrome Mobile"
You can read more at
As a site owner, how do I opt-out from content optimization?
Data compression proxy respects the standard Cache-Control: no-transform directive. Site owners can mark individual resources with this directive and the proxy will pass them through directly to the browser.