Multiple Tiwaz runes either stacked atop one another to resemble a tree-like shape, or repeated after one another, appear several times in Germanic paganism:
The charm (alu) on the Lindholm amulet, dated from the 2nd to the 4th century contains three consecutive t runes, has been interpreted as an invocation of Tyr.
The Kylver Stone (400 AD, Gotland) features 8 stacked Tiwaz runes at the end of an Elder Futhark inscription.
From 500 AD, a Scandinavian C-bracteate (Seeland-II-C) features an Elder Futhark inscription ending with three stacked Tiwaz runes.
Info from Wikipedia