When the browser send cookies not received from the server?
<p>Working on a web application, I noticed that some visitors browsers send to the server cookies not received previously from my scripts. </p>

<p>My scripts set only session cookies and only for users logged in, so these visitors guaranteed have no my cookies set in their browser.</p>

<p>I don't have JS on the site. Plain HTML+CSS.</p>

<p>The browsers behaving this way are Chrome and Safari. </p>

<p>How this can happen? What are these cookies?</p>

<p>Should I display a warning message for these visitors that their browser behaves strange?</p>