The two sides are reportedly holding talks to stave off legal action after Orange objected to the corporate colour of Haji-Ioannou's latest venture, easyMobile.
Philip Towler, a partner with trademark specialist law firm Frank B Dehn & Co, told the Independent: "If Orange and easyGroup end up in court, one issue is likely to be whether the two shades of orange are similar enough to confuse the public."
He added that while it is unlikely that Orange will gain exclusive rights to all shades of orange, ultimately it is up to the courts to decide.
Orange has registered its colour, known as Pantone 151, while easyGroup's colour is Pantone 021.
Companies that have also registered colours are likely to be keeping a close eye on events. These include London Transport, which has registered the red of its London buses, and the AA, which has exclusive rights to use its distinctive yellow shade on its recovery vehicles.
This is the latest setback to hit the planned launch of easyMobile; earlier this week it was revealed the venture does not have a UK network to carry its calls.
Haji-Ioannou's deal with Danish telecoms company TDC covers 12 European countries but does not include the UK.
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