The high number of shades found on the US 2¢ Andrew Jackson "Bank Note" stamps (such as #146) is primarily due to the inconsistent production methods and environmental vulnerabilities of 19th-century printing. Because of this I would advise attempting to identify the large banknote 2¢ stamp by its color. The shade of red-brown does not affect its value.
While the official colour for these issues is often listed as red-brown, collectors frequently encounter a vast spectrum ranging from bright to dull hues.

Key Reasons for Shade Variations
Manual Ink Mixing: In the 1870s, inks were mixed by hand in large batches. Small differences in the ratio of pigments, oils, and dryers between print runs led to noticeable shifts in the final shade of blue.
Multiple Printing Companies: The "Bank Note" series was produced by three different companies over nearly two decades: National Bank Note Co. (1870–1873), Continental Bank Note Co. (1873–1879), and American Bank Note Co. (1879 onwards). Each company used its own ink formulas and printing equipment, further diversifying the available shades.
Ink and Paper Sensitivity: The red-brown pigments used during this era were highly susceptible to environmental changes. Factors such as humidity, temperature in the press room (which affected ink thickness), and exposure to sunlight (fading) have altered the stamps' appearance over the last 150 years. Some plates received heavier or lighter applications, changing the final shade.