"I'm doing this for two hours." and "I've been doing this for two hours."

[ahsanul.irfan]

"I'm doing this for two hours."
"I've been doing this for two hours."

Do these two mean the same?

 

[5jj]

No.

The first means that you have started something that will go on for a total of two hours.
The second means that you started something two hours ago and have been doing it for that time.

 

[Yankee]

"I'm doing this for two hours."
"I've been doing this for two hours."

Do these two mean the same?

They could, depending on status of the "doing".

 

[emsr2d2]

They could, depending on status of the "doing".

I can't see how they can mean the same, whether they're uttered at the same point in time of the "doing" or not.

 

[Tdol]

They could, depending on status of the "doing".

That would be a hard sell in British English.