Yes, there are two ways:
If you have a single-device subscription, and you're copying your data from an old device to a new device, you'll upload the data from the original device, unregister that device, login to your account from the new device, and then download the data you previously uploaded.
If you have a multi-device subscription, you log both devices into your account, upload data from one, and then download those data to the second.
Within iFly (once the device is logged in):
- To upload the data from the device you want to share from: Menu > Setup > Sync Devices... > Upload files to server, make sure "Custom Waypoints" is checked (along with any other data you want to share or backup), then click "Upload".
- To download the previously-updated data on a different device: Menu > Setup > Sync Devices..., select the device whose data you want to download, then check the boxes for the data you want to download and click "Download"
Note that the iFly cloud holds the data from your different devices separately--it doesn't all get intermingled or overwritten there. So on any given device you're trying to configure, you can opt to download different data from different devices and mix-and-match however you choose.