There is some simple maths to be used here. A 50% chance of winning is 0.5 as a decimal. 0.5 to the power of 6 = 0.015625, which is a 1.56% chance that you will lose 6 times in a row. As you can see, highly unlikely but at a stretch still could happen. Losing 20 times in a row, however, gives a chance of 0.5^20=0.000000953674316, or 0.0000095%. As you can see, this would realistically never happen. Now 100 times in a row is ridiculous, and this would absolutely never ever happen unless billions of people played on the server. 0.5^100=0.00000000000000000000000000000078886091, or 0.000000000000000000000000000078886091%. You could not possible lose 100 times in a row.
So, back to your question, it is highly unlikely that a perfectly random system would give you 6 heads and 6 tails, so it is likely that the coinflip system is flawed and has a tactical way to win more times than others.
Sincerely, the Businessman.