Oh yes, it is two pieces attached by a wafer while still hot. This was standard procedure at most if not all glassworks in U.S.A at the time and later. Sandwich an avid practitioner of this method, even candlesticks made with different sockets attached to variety of bases, as well as compotes, cake stands, vases, lamps etc. Some time around 1870 this began to change with most glassworks in a gradual way, but still carried on for larger pieces for another decade. You might say a defining aspect of some American EAPG. Pictured a cake stand, design patented 1870, obvious wafer attachment.