Why are we seeing multiple devices on a single domain_userid?

We see multiple devices for a single domain_userid. Since this is assigned by placing a cookie the first time someone visits the site on each device, we are confused how this is happening.

One theory is that people are logged in to a certain browser on both devices, so then snowplow sees the same cookie. Is this a likely reason?

No this shouldn’t happen. Provided you’re not messing with the default behaviour, you shouldn’t see duplicate domain_userid across different devices.

How have you determined this is happening? Is it different user_agent strings with the same domain_userid or something else?

Send through some samples of this (sanitize the data if necessary).

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Hi, Thanks so much for your reply!

I have determined this from the dvce_type and the useragent. They are both different.

Here is an example:
domain_userid dvce_type useragent count
XXX Mobile Mozilla/5.0 (Linux; Android 7.0; SAMSUNG SM-G930F Build/NRD90M) AppleWebKit/537.36 (KHTML, like Gecko) SamsungBrowser/5.4 Chrome/51.0.2704.106 Mobile Safari/537.36 184
XXX Computer Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) SamsungBrowser/5.4 Chrome/51.0.2704.106 Safari/537.36 57

both of these lines had the same domain_userid, but as you can see, one appears to be on mobile and the other on a computer.

Let me know if there is anything else I can provide you with

Could it be e.g. a bot spoofing different useragent strings? What is the pattern of the behaviour? Does the “device” change at a single point in time? Or does it flit between device types?

Is there anything “bot like” in the event stream for that domain_userid? (E.g. the events fire at very regular frequencies, or frequencies that are too high to be a human?)


I would also analyse if browser quersy string changes durning the session - in other words assume domain_userid to be OK and validate if session looks like expected and what happens with devices.