No, you're not seeing double. Southampton's twin White Sisters are set to change the face of British cruising and the city's port in the years to come.

The two identical ships, Oceana and Adonia, will be together for the first time in Southampton Docks next week, each at the start of a bright, brand new career.

From the outside the two superliners may look the same but on board they are very different, each with their own style, personality and atmosphere.

Oceana combines glamour and family fun while Adonia is dedicated to adults-only and is the most contemporary ship in the company's fleet.

The ships will make a spectacular sight bow-to-bow at 102 and 103 berths in the city's Western Docks on Wednesday for the first double Royal naming ceremony of this kind ever to be held in the UK. Their sleek lines and distinctive curved funnels will make a dramatic backdrop for the evening event, during which the Princess Royal will name Oceana while her daughter Zara Phillips will do the same for Adonia.

After being met on the quayside by Oceana's master Captain Steve Burgoine and Captain Rory Smith in command of Adonia, the Royal party will be taken on board the two vessels for a guided tour.

The Princess Royal will go behind the scenes and visit the bridge on board Oceana to meet members of the crew while Zara will have the chance to do the same on Adonia.

Altogether around 2,000 guests, including VIPs from as far away as Australia, India and the US, will attend a gala reception and dinner on board the ships before the actual dockside naming ceremony.

Among the guests will be Southampton's very own super Saint, Matthew Le Tissier, who will be mingling with ambassadors, shipping magnates, show business personalities including Linda Bellingham, and captains of industry.

Continuing the doubles theme, the twin comperes for the ceremony, starting at around 9.30pm, will be British rowing champions Matthew Pinsent and James Cracknell, who have often competed together in the same boat.

A light show will be projected on to the two White Sisters as the guests watch a dazzling dockside production, also highlighting mirror images and double acts, before a short religious service and the christening ceremony.

The namings will take place separately and in alphabetical order with Adonia being the first to be named, followed by Oceana.

Zara will initially to say the emotive words: "May God bless her and all who sail in her,'' and then the Princess Royal will repeat the ceremony before two traditional bottles of champagne are sent crashing against the hulls of the vessels simultaneously.

Two military bands, including the Royal Marines, will be providing the music and singers of the Southampton University Gospel Choir will also be performing during the ceremony.

The whole event culminates in a huge fireworks display at around 10pm as rockets soar above the ships and light up the night sky over the docks in a glittering display.