I suggest you add a volume name (label) to the partition or partitions on the USB pendrive. This way, when you hover over the icon on the launcher it will display the volume name so you know which is the correct device.
You can add or change the volume name using Disk Utility. Select the correct drive in Disk Utility, then click on the unmount button. Next click the 'edit filesystem label' button and change the name to something meaningful to you. You can now mount the device again with the mount button and it will appear in the launcher with the correct label when you hover over it.
This is Disk Utility with the pendrive selected in the left frame. To the right of this you can unmount the device and then change the label, then remount it again. The pendrive in this example now has the label "white8" and its mount point is /media/white8
Now when you hover the mouse pointer over the device in the launcher it shows the label name so that you can recognise it.