To chain key presses together as `N key presses per X milliseconds`

you can use the following structure:

```
key::
x = ;milliseconds
if n > 0
{
n += 1
return
}
n = 1
SetTimer, Chain, %x%
return
Chain:
SetTimer, Chain, off
if n = 1
{
;if key was pressed 1x
}
else if n = 2
{
;if key was pressed 2x
}
else if n > 2
{
;if key was pressed 3x or more
}
n = 0
return
```

So, based on your example, we have:

```
#1::
x = 900
if n > 0
{
n += 1
return
}
n = 1
SetTimer, Chain, %x%
return
Chain:
SetTimer, Chain, off
if n = 1
{
Send, hey
}
else if n = 2
{
Send, hi
}
n = 0
return
```