Why might currencies issued by the many state banks have caused confusion before the Civil War?

During pre-Civil War times in the United States, banks around the country issued bank notes as a form of currency. The large number of banks led to a large number of diverse bank notes that circulated around the country. Although many banks issued only enough bank notes that could be backed up by specie (gold and silver during the time), riskier banks gave into temptation and issued more than they could cover. This practice caused many people to doubt the exact worth of certain notes and in turn have little faith in some banks.