We had this discussion a while ago. Dave Greenhalgh was here saying you only had one blow with the hammer, which is unquestionably true for small coins (he does this all the time). The hammer can bounce leading to double striking, but I think the question of more than one blow could apply to larger modules. I used my type 5 halfcrown as an example, see below.
There is unquestionable double striking by the horse's rump and by the S on the obverse, and the N & H on the reverse. The relief of the obverse has a significant change of angle which is obvious with the lighting, and a similar profile change in the diametrically opposed part of the flan. I couldn't see how a bounced strike could produce such a large change of angle whilst still producing what is quite a well struck up coin.
Looking to pick holes in my thoughts, the only way you could get this profile with a double change of angle would be if the die was cut with the angles as seen, which isn't impossible. Although it is counter-intuitive to presume the die was engraved on a deliberately non-planar surface, I suppose an angled profile such as this would constrain movement along the 1 o'clock/7 o'clock axis, but the lower and less angled profile on the 10 o'clock/4 o'clock axis would allow some lateral movement. The double striking seen on this coin would agree with the above, so maybe I'm wrong in thinking it was struck more than once. Don't have a ouija board to find out.