That was my idea!

I've had a number of ideas over the years that I have researched only to find that it has already been done.  In some cases what has already been achieved surpasses what I had intended, but in others it falls short of what I would have wanted.  In these scenarios I don't think either should discourage you from pursuing an idea.  Competition is healthy and leads to choice.  Failure to have competition leads to monopolization and exploitation, even extortion.

Moving away from the competitive aspect however there is something which is at play here which I have often taken issue with.  There is an idea that what you imagine has to be original to be worthy of merit or credit.  I take issue with this for a number of reasons but the crux of my argument is simply, if you had no idea that it already existed, and you were not influenced by he existing idea, then you should be given merit for what you can come up with, and in some cases you should still be credited with the idea - even if it was already done. 

As an example the modern day battery was largely developed as a result of a complex process of engineering, it stems from the Leyden Jar described by Benjamin Franklin in 1748.  This is an example of an individual who had an idea and was given both merit and credit for it, as they were seen as the first person to create it, and did so with no previous exposure to the concept.

However this was not the first battery that existed.  There have been several others throughout history and the most notable is the Baghdad Battery dating as far back as 250 BC, some 2,000 years before Franklin had the same idea.  The use of the Baghdad Battery does not change what it could be used for - it was capable of being used for electroplating gold and silver however this is now dismissed as its possible use for the time period; this dismissal does not change the design of the object however, what it was capable of, and crucially it does not change the fact that it was a battery.

Who should be given credit and who should be given merit for creating the battery?  If you pick one over the other I would say you are showing bias.  Both are deserving, regardless of who was first, and regardless of how they intended their creations to be used.  They both had the same idea, independent of one another.  The inventive process and the creativity and ingenuity should be praised in itself, and should not be validated nor invalidated by which came first.