"Last seen" on WhatsApp for same contacts on different phones is not shown I have 2 phones with 2 different WhatsApp accounts, not linked to each other at all.
Let's say I've got 3 contacts, contact X, contact Y, and contact Z on my WhatsApp profile &quot;A&quot; on phone &quot;A&quot;, and the same 3 contacts on my WhatsApp profile &quot;B&quot; on phone &quot;B&quot;.

I can see contact X &quot;last seen&quot; time and date on the WhatsApp profile &quot;A&quot; on phone &quot;A&quot;, but at the same time not see contact X &quot;last seen&quot; time and date on the WhatsApp profile &quot;B&quot; on phone &quot;B&quot; of mine.
I can however see on WhatsApp profile &quot;A&quot; &amp; &quot;B&quot; when contact X is online as both WhatsApp profiles &quot;A&quot; &amp; &quot;B&quot; simultaneously indicate &quot;online&quot; when contact X is online.
For contacts Y &amp; Z, I can see the &quot;last seen&quot; time and date as well as &quot;online&quot; simultaneously on WhatsApp profile &quot;A&quot; &amp; &quot;B&quot; on phones &quot;A&quot; &amp; &quot;B&quot;.

Why would it be that I can see contact X's &quot;last seen&quot; time and date on WhatsApp profile &quot;A&quot; but not on WhatsApp profile &quot;B&quot; while I can see the &quot;last seen&quot; time and date of contacts Y &amp; Z on both &quot;A&quot; &amp; &quot;B&quot; WhatsApp profiles?
Other contacts which are also on both WhatsApp profiles of mine, I can see the &quot;last seen&quot; time and date on both WhatsApp profiles.
There is a setting, which allows you to control who can see your "read receipt" or your "last seen" (or a few other settings).

You find this settings under:
WhatsApp > Menu Button > Settings > Account > Privacy.

Following settings are possible: Everyone, My Contacts, Private.

To summarize your described behavior: Your observed person must have one of your numbers in his contact list, and has selected "My Contacts" for this settings (regarding "last seen"). So you are able to see the "last seen" from the number, they have in his contact list. But not from your additional number

For additional information you can visit https://www.whatsapp.com/faq/en/android/23225461