Hard to find bases like this as a pair, see tape measure. Not positive but I believe these are Pittsburgh. Matching pair except one is a mustard color and the other has a copper color that almost looks like it was applied over the same mustard color.
Not sure if this is factory finish or not. The item "Pair Matching PITTSBURGH LAMP BASE Art Nouveau Arts & Crafts reverse painted" is in sale since Wednesday, April 7, 2021. This item is in the category "Antiques\Decorative Arts\Lamps". The seller is "slatebeltsalvagetony" and is located in Bangor, Pennsylvania.This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Brazil, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Ecuador, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Peru, Pakistan, Paraguay, Reunion, Viet nam, Uruguay.