Are These Two Different Numeral 6 On Scott J94?

the top tails seem different.

Over the long span of production, a replacement "mat" was made to print the black portion. They vary slightly in the spacing/alignment of the number and text. You appear to have one of each. Note the 6 has a slightly different horizontal alignment to the text below. Also, these mats are rubber, rather than metal, so differences in pressure will alter the impression somewhat.
The 6 cent issue was written-up in the United States Specialist in the issues of Feb 1997 (pp74-76) and July 1997 (page 299). Other denominations were also covered in the Specialst in the 1995-1999 time span.

thanks John I didn't notice the alignment but now I see the tilt to the right on the 6 is more on the right one.

As an example to show how much these stamps can vary in appearance on a single pane, here is a rolled-up partial pane of J100 on the scanner bed to show how I mde the second image


The resultant scan aligns the 10th column (now at left) with the first column (now at right). Quite a difference across a single pane!!