I have never come across dummy tanks used in WW1 to confuse aerial recce. This was primarily a WW2 feature. However the Germans used a number of wooden replicas of British tanks for training. Some were mounted on punts so they could float across the view - these were use for training artillery used for anti tank work. The Australians in 1918 used some realistic wood and canvas dummies to fool the Germans that they (the Australians) had more tanks in support that they had and that a tank attack would be coming from a specific (false) direction (thus pinning down enemy forces) The dummy tanks were manouvered by men inside them - a risky business as the dummies attracted fire.
The Australians used dummies in Australia for fund raising. I have identified at least five different models. Dummies were also used in the US (including Orange County Cal, San Diego, New York State, New York and Cleveland) all (except possibly the San Diego one) for selling Liberty Bonds. (A real British tank also toured the USA at this time raising a significant amount of money). Canada had a tank based on a truck which was used in 1917 for recruitment and fund raising in Hamilton and Toronto (later sold to the USA) but also was visited by a real tank. New Zealand had at least one fund raising dummy. At least two dummies were used in Britain for fund raising in Wales and Scotland (although the real touring tanks (tank banks) raised millions .
