Hello @Neziak & @joelbean,
With the Cat-18 Chipsets, you need to have four (4) antenna connections, so having enough real estate space to fit these onto the connector plate is a challenge with the MAX Transit range, so you are unlikely to see a Cat-18 DUO.
What you may find as a suitable alternative are the MAX Transit DUO Cat-12 model. Talk with you local Peplink Partner about the suitability of these if you want the dual modem in the compact MAX Transit form factor, otherwise as @MartinLangmaid has mentioned the new MBX HD2 with Cat-18 will be the suitable alternative for the MAX Transit DUO going forward.
Happy to Help,