You can only have up to one clue of each tier active at any one time. There is a soft cap of 25 on sealed clues for each tier, but guaranteed sources bypass this. The cap can be increased to 50 of each tier by buying the Clue capacity upgrade from Zaida.
It is possible to turn off specific levels of sealed clue scrolls and/or their loot beams via the game settings interface.
There are the following levels of sealed clue scrolls: