ALL OVER AGAIN

Six letter words which repeat themselves:

1 motmot (tropical bird)
2 cancan (French dance)
3 dumdum (soft-nosed bullet)
4 bye-bye (form of goodbye)
5 zoozoo (a dove or pigeon, sometimes zouzou)
6 haw-haw (a ha-ha, a fenced ditch)
7 chichi (self-consciously stylish)
8 akeake (type of tree)
9 valval (relating to a valve)
10 grigri (African amulet)
11 tzatza (Black Sea fish)
12 humhum (cotton cloth)
13 mulmul (muslin cloth)
14 boo-boo (a blunder or a blemish)
15 kai-kai (a Maori feast)
16 tut-tut (to rebuke)
17 atlatl (a central American throwing-stick)
18 beebee (type of parrot)
19 goo-goo (babies' noise)
20 hee-hee (laughing sound)
21 palpal (of a palp, an insect's sense-organ)
22 piupiu (Maori ceremonial skirt)
23 jigjig (a jolting motion)
24 lablab (tropical bean)
25 pawpaw (tree / fruit)
26 tomtom (a hand drum)
27 tartar (chemical substance)
28 yum-yum (expressing delight at food)
29 gru-gru (palm tree)
30 tsetse (African fly)
31 wee-wee (to urinate)
32 murmur (soft vocal sound)
33 cha-cha (Latin American dance)
34 laplap (a taro/yam dish)
35 furfur (dandruff)
36 Berber (N African people / language)
37 sarsar (cold Middle-Eastern wind)
38 foo-foo (mashed cassava)
39 bulbul (songbird)
40 coocoo (Armenian pie, also variant of 'cuckoo')
41 testes (reproductive organs)
42 chocho (tropical tree)
43 muu-muu (Hawaiian gown)
44 aye-aye (type of lemur)
45 semsem (another word for sesame)
46 waw-waw (a wailing sound, same as wah-wah, in musical terms)
47 dik-dik (small African antelope)
48 tuk-tuk (Asian three-wheeled vehicle)
49 mam-mam (child's word for grandmother, also nan-nan)
50 sesses (same as cesses, old word for local taxes)
51 toitoi (New Zealand grass, also spelled toetoe)
52 bonbon (a sweet)
53 loglog (the logarithm of a logarithm)
54 cuscus (millet grain, also spelled 'couscous')
55 kumkum (red powder used to mark the forehead)
56 boubou (an African shrike or a long African garment)
57 pip-pip (a sign-off or goodbye)
58 ulaula (a hibiscus flower or a fish, from the Hawaiian for red)
59 tam-tam (a gong)
60 dugdug (tree of the Pacific islands)

Source: various