Cannot say for sure for the C9300, but on some other older Catalyst switches, SFP+ ports has both gig and 10g ports for the same physical port. I.e., it looks like two physical ports, but there's only one. Which you configure, depends on whether you install a SFP or SFP+ optical transceiver.
why is that difference?
In the past, the ports only appear only when an optics is inserted. For example, if a GLC-SX-MM is inserted, the port Gi1/1/1 to Gi 1/1/8 will appear and can be configured. If a SFP-10G-SR is in inserted, Ten 1/1/1 to Ten1/1/8 will appear and Gi 1/1/1 to Gi 1/1/8 will disappear.
This change was only introduced after customers could not "pre-provision" the ports if the NM nor the optics is not enabled.
To some degree, it makes sense but it can also be confusing because now, any optics, regards of 1- or 10 Gbps, is now "Ten".