Interesting occurrence from a hazard

Just yesterday (21 December 2016), I was playing in a group when a very unusual play happened.

It took place on the 5th hole at Pelican Waters, which for those who know it, is a hole featuring a water crossing (burn) about 65 metres from the green.  It is a hole where many people come to grief as they often hit their second (or sometimes 3rd) shot into the water.  It is a risk/reward hole if you are more than 140 metres from the pin, so many players take the option of laying up.  At the moment, the water crossing is dry and you are able to walk across it.

Back to the incident in hand – one of the players in our group had a second shot of about 160 metres to the back pin, but pulled his shot to the lift and it crossed over the water crossing, hit the bank and rolled down into the hazard, sitting on top of the muddy surface.  It was quite playable so he proceeded to play it like a bunker shot, taking a heap of dirt as he swung hard at it.  His ball ballooned into the air, landed on the green and finished about 7 metres away from the pin.  The rest of the group applauded the shot, but were then surprised when the next minute the player hit another ball from the same area and it skidded across the green and ended up in front of one of our players who casually knocked it away off the green.  The player who hit the ball called out “What are you doing?”, and the reply was along the lines of why did you hit this second ball?

It transpired that the player did not realise that his first ball had actually landed on the green, but after he hit it, another ball appeared half a metre in front of him and he thought it was his original ball, so he played it.  This second ball must have been buried underneath his first ball and popped out as he hit it.

Not being 100% certain as to how to proceed, I suggested that he be penalised for practising on the course, penalised 2 strokes and to play his original ball, which he subsequently one putted.

What would your decision have been?

Post script:  some good discussion resulted from this post, and thanks for the comments.  I received a succinct reply from Barry Rhodes, the Rules guru, who agreed with Roger that it was a simple case of hitting a wrong ball, which is a 2 shot penalty, and play should proceed with the original ball.

I just want to add that it all happened so quickly, with the player originally identifying the ball as his, playing at it, then thinking that he only moved his ball a short way, so he then immediately played at that ball, which we then realised was not his.  He did not know at this stage, and that is why we asked why he had played the other ball when his first ball was already on the green, which he did not know.

No further discussion needed.  However, here is a “spanner” to throw into the works.  Say a  player hits his ball into the same hazard, and it is playable and he intends to play it as it lies, since the water has receded.  Before playing his ball, he notices there are quite a few balls half buried that have been exposed by the water receding.  He proceeds to pick up some of these balls, digging them out of the dirt with his wedge and throwing them on the grass to pick up later.  He then plays his ball from within the hazard.

Any penalty apply here?