Doubt! Please, help me!

[Apollo_Doutrinador]

Hello friends, I am Brazilian and I have a doubt in this text:
Steve Harris says: “When we did our first couple of gigs at the Cart and Horses, we had a phone call behind the bar one night, and still to this day I don't know whether it was a fucking wind-up or what, but someone phoned up and said, 'We're called Iron Maiden and you can't use the name,' and all this, but I just said, 'That's tough shit, because we're called Iron Maiden, so bollocks!' I must admit, I was all bravado on the phone, but when I came away I thought, 'Oh shit,' 'cause if they had registered it - you know, even though we were only playing pubs - then we wouldn't have been able to use it, and by then I was really set on it. But we never actually heard any more, so it might have been one of my mates winding me up, doing a northern accent. I don't know." (IRON MAIDEN OFFICIAL BIOGRAPHY 1998)
In this text, Steve Harris:

A) DON’T known about the existence of other band called “iron maiden” before the phone call. He didn't know if the person on the phone was joking or serious about the existence (or not)of other band called "iron maiden

B) Known about the existence of other band called “iron maiden” before the phone call. He didn't know if the person on the phone was joking or serious about this other band registered or not the name "iron maiden". (In this case, he known about other band called iron maiden BEFORE the phone call)

[RonBee]

What do you think?

(Say: "He didn't know about the existence of the other band beforehand.")

(I rarely hear the word "doubt" in everyday life, but sometimes I hear the word "question".)

[Apollo_Doutrinador]

What do you think?

(Say: "He didn't know about the existence of the other band beforehand.")

(I rarely hear the word "doubt" in everyday life, but sometimes I hear the word "question".)

So, in your opinion, He didn't know about the existence of the other band??

[RonBee]

So, in your opinion, He didn't know about the existence of the other band??

You may think that if you wish, but I said:

What do you think?

It's all in the text. Reread it. (It's not written in a way that's confusing at all.)

(Say: "He knew about....")

[Apollo_Doutrinador]

You may think that if you wish, but I said:

What do you think?

It's all in the text. Reread it. (It's not written in a way that's confusing at all.)

(Say: "He knew about....")

In my opinion, He didn't know about the existence of the other band called iron maiden. But I don't have certainty.

Sorry for my bad english. I'm beginner in the english language.

But, what your opinion about this text?

(thank you for your attention)

[RonBee]

In my opinion, He didn't know about the existence of the other band called Iron Maiden. But I don't have certainty.

There! But why aren't you sure?

[Apollo_Doutrinador]

There! But why aren't you sure?

“still to this day I DON’T KNOW whether it was a fucking wind-up or what”
“But we never actually heard any more, so it might have been one of my mates winding me up, doing a northern accent. I DON’T KNOW”
My doubt is:
A) He didn't know if the person on the phone was joking or serious about the EXISTENCE of another band called “iron maiden”
B) He didn't know if the person on the phone was joking or serious about the other band REGISTERED (or not registered) the name. He know about the existence of other band called “iron maiden”.

[RonBee]

B) He didn't know if the person on the phone was joking or serious about the another band REGISTERED (or not registered) by that name. He didn't know about the existence of another band called “iron maiden”.

[Apollo_Doutrinador]

B) ???

you are correcting me or answering my question? Why do not you answer me what is your opinion? You think that the correct answer is the A or B? why?

You think the correct question is A??? WHY?
You think the correct question is B??? WHY?

Why you do not clearly explain your opinion about the correct question? Please!

you can clearly explain to me finish my doubt?

[RonBee]

I thought you had figured it out, but as it turned out I was wrong. As it is clear from the text, Mr. Harris did not know of the existence of another band called Iron Maiden when he received the phone call in question.