Do UK manufacturers need both CE and UKCA marks simultaneously?

Yes, if you want to supply both the UK and European markets, you cannot avoid both marks. For sales within the UK, the UKCA marking is sufficient, but for export to EU member states, you need the CE marking as well, since the EU does not recognise UKCA. In practice, this means two conformity assessment procedures, potentially two different testing bodies and duplicate technical documentation, with slightly different requirements depending on product category. Many manufacturers therefore run both tests in parallel at appropriately accredited bodies to consolidate effort and avoid delays in market access.