From a mathematical point of view, it does not mean that "XX is a double YY" means that XX has a double YY.
And double is understood as 1+ 1 times, which can be understood as follows: double is twice, of course twice!
Strictly speaking, this is a narrative problem:
(1)A is q times that of B.
(2)A' is q times larger than B'
There is a difference. In (1), if B= 1,
Q=2 then A= 1*2=2.
And in (2), the same B= 1.
Q=2
But A= 1*( 1+2)=3.
The difference lies in the difference between "yes" and "many". If you change "many" to "yes", you should add one to the multiple, as shown in the figure; (The string is double)
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1 time
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Twice as much as "-"and 2- 1= 1 times as much as "-"
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Twice as much as "-",yes
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"2+ 1=3 times.
Then, the difference between double and double can be understood as the difference between one copy and two copies.