Thank you for reaching out to us. Yes you can perform device swaps between two phone lines on your account by logging onto your Sprint online account. When logged into your account click on My Services and Device tab, choose the blue link "Change device on my profile" (this can be located near the icon representing your current device), a pop-up will appear giving you options on how you would like to perform the device change. If the pop-up doesn’t appear make sure to turn off your pop-up blocker. Let us know if you have any additional questions.
Sprint Social Care Team