Is "Yeh meri apni swayam ki kitaab hai" correct?

Why

Nikhil's instinct — that repeating a word-like idea adds emphasis — works in some contexts (like adding an intensifier), but not when the two words already mean exactly the same thing. 'अपनी' and 'स्वयं' both express the same idea of ownership/self — saying them together doesn't add force, it just repeats the same information twice, which Hindi grammar treats as a flaw called पुनरुक्ति दोष (redundancy error), the same category of mistake as saying 'अपना स्वयं' or 'सर्वसम्मति से सबने' (where both halves already mean 'everyone agreed'). The fix is to keep only one: 'यह मेरी अपनी किताब है' or 'यह मेरी स्वयं की किताब है', either alone is complete and correct. Test it: try removing 'स्वयं' — 'यह मेरी अपनी किताब है' loses nothing; removing 'अपनी' also loses nothing — a true sign both were saying the same thing. His sister is right: 'अपनी' and 'स्वयं' repeat the same meaning — this is पुनरुक्ति दोष, and only one of the two words should be used.