Colm Murphy and Seamus Daly were ordered to face a retrial after they successfully appealed a finding of liability against them in the original case in Belfast High Court.
But their second trial delivered the same outcome in the same court, with judge Mr Justice John Gillen ruling the men were responsible for the 1998 Real IRA attack.
The attack killed 29 people, including a woman pregnant with twins, when a dissident republican car bomb ripped through the Co Tyrone town on 15 August 1998. More than 200 were injured in the blast.
No-one has been criminally convicted of the bombing.
However, in 2009 Murphy, a builder and publican from Dundalk, Co Louth, and Daly, a bricklayer from Culloville, Co Monaghan, and two others were held responsible in the initial civil action taken by some of the bereaved families.
Along with Real IRA leader Michael McKevitt and Co Louth republican Liam Campbell, the men were ordered to pay £1.6m in damages.
McKevitt, who is serving a 20-year prison sentence in the Republic of Ireland for directing terrorism, and Campbell, who recently successfully fought extradition proceedings to Lithuania on arms smuggling charges, failed in their bids to overturn the Omagh civil judgment.
They are now seeking to have their case heard in the European Court of Human Rights.
Murphy and Daly's appeals were upheld, but both men were ordered to face another trial.
The retrial started in January and finished last month, with Mr Justice Gillen delivering his reserved judgment today.