In streams supporting both read and write, you actually have two positions, one for read (i.e. “get” denoted by “g”) and one for write (i.e. “put” denoted by a “p”).
And that’s why you have a seekp (inherited from basic_ostream), and a seekg (inherited from basic_istream).
Side note: The language C has – in contrast to C++ – only one such function fseek for both pointers; There it is necessary to re-position the pointer when switching from read to write and vice versa (cf., for example, this answer). To avoid this, C++ offers separate functions for read and write, respectively.