Firstly, it's the same way to pronounce, no matter it's a '3rd-tone 3rd-tone' word or two sepatate single-syllable words combined in a sound group.
The so called 3rd tone is actually seldom pronounced as 214, except that there is acccent/stress (of sentence of word) on it.
Examples of 3rd-tone 3rd-tone' combinations:
整理，稳妥，总理，海水，水手； 想你，你好，好懒，鸟岛： 35214
你好，我好，大家好： 35214 35214 5155215
你好我也好： 35214 3535214.
As a matter of fact, the syllables described as 35 and 214 tones in the phrases above are not so exactly what they are in the real spoken language, but this does not matter so much.
Examples of ‘three-3rd-tone’combinations: