You can add only one Tasks Table to a particular experiment. All the tasks you create, gets added to the same table. Once a user adds a tasks table, the properties that appear in the table are based on the first selected template. If a user adds a new task using a different task template, since all created tasks gets added under the same Tasks table information item, only the properties of the first selected template remain showing even if the other selected templates have different properties.
All additional properties get added under the Hidden list allowing the users to add them manually if desired. If you want to replace the first selected template with a different one, you can either delete the current table, create a new one and select the template that you want or you can keep the existing table, create a new experiment and add a new Tasks table.