Hi,
If you're comparing model results forced by TPXO data with TPXO data, it's normal you have similar results. Note that tidal currents computed by Telemac are often better than TPXO ones.
I advise you to understand what are the main physical process in your area, and compare your model results with in-situ measurements instead (tide gage, ADCP...).
Telemac is used to increase the accuracy of the results in nearshore area where TPXO database is not accurate enough (tidal estuary, harbor, beach...).
Telemac can especially allow you to add other physical processes than tide: regional circulation, meteorological effects (wind/pressure), wave effects, river contribution... and to compute resulting tracers behaviours for instance.
If you only need a surface elevation signal resulting from tide only (no meteo), TPXO can be enough.
Regards,
Laurent