1908 plates were made of separate metal panels - one for each digit, and one for the right side with the makers seal.
Some 5-digit plates had the first two digits on the same panel.

Here is a set of 4 plates with the same number.
The makers seals on one set have the serial number 480 ... the second set has ☆480☆
Maybe the star denotes a second set of plates (remakes) ??
Leib Brothers

Below is a 1908 plate with two seals on it.
Does that mean it was transferred to a different car mid-year ?   Perhaps we'll never know.
John Anshant