Can simeone explain what this means on whatsapp?

[Anonymous]

My boyfriend has auto delete on his what's app. Which also deletes messages on my end.
But sometimes his text to me has a little white mark at the end. I clicked on it and it said this message will not disappear thecwhatscapp user may be using an older version of what's app.
Does he have 2 what's app accounts on his phone?

[Ευδεμονια]

I think honestly, first of all, that’s strange one has to cancel everything on WhatsApp. I think he’s hiding something.
And the fact he has 2 WhatsApp accounts (maybe he has 2sim cards, does he have a multiple SIM card phone?) is very suspicious.