Indirect statement WITH double accusative? LLPSI, XXI, Pensum B.

Salvete.

I’m looking at Pensum B and filling in the blanks I think there is a sentence which reads:-

Puer matri tabellam Sexti ostendit et ‘se ipsum eas litteras scribere’ dicit.

I’m feeling quite confident about the blanks I’ve filled in and the meaning of the sentence. My doubt and the question about which I’d welcome any pointers is regarding the indirect statement. I’m wondering if this is an example of a double accusative? If it is then of what kind might it be?

I realise that I may have missed the obvious or simply be overthinking this but I’d like to understand what’s going on grammatically so that I can move on and not feel like I’m cheating myself. My thanks to anyone whose kind enough to assist.

In Latin you often get two accusatives, one the subject of an infinitive and the other the object of it. E.g. Puella dixit se hoc dixisse, The girl said that she’d said this, or Video te ipsum eas litteras scribere, I see you’re writing that letter yourself.

Thanks ever so much.