how many times have two players had 15 rebounds in the same game

Tom Chambers had 9 games played with 15+ rebounds.

Interpreted as:

How many times in the regular season have two players had 15 or more rebounds in the same game?

	NAME	GP	REB	MPG	PPG	RPG	APG	SPG	BPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	TS%	OREB	DREB	TPG	MIN	PTS	AST	STL	BLK	TOV	PF	+/-
1	Tom Chambers T. Chambers	9	147	42.1	24.4	16.3	2.2	0.6	0.8	8.9	21.9	40.6	0.3	0.8	42.9	6.3	8.2	77.0	47.9	4.9	11.4	3.0	379	220	20	5	7	27	35
2	James Edwards J. Edwards	3	50	37.7	26.7	16.7	2.7	0.0	0.7	9.0	21.3	42.2	0.0	0.0		8.7	13.3	65.0	49.0	6.3	10.3	3.0	113	80	8	0	2	9	14
3	Artis Gilmore A. Gilmore	60	1,027	37.7	20.1	17.1	2.0	0.5	2.5	7.4	11.8	63.0	0.0	0.0	0.0	5.2	7.2	72.3	67.0			3.0	2,263	1,203	119	30	151	179	201
4	Moses Malone M. Malone	178	3,138	38.1	25.2	17.6	1.4		1.6	8.4	17.9	46.7	0.0	0.1	0.0	8.5	10.8	78.5	55.6				6,786	4,481	257		278		447
5	Truck Robinson T. Robinson	9	150	37.9	15.0	16.7	2.3			6.8	13.9	48.8	0.0	0.0		1.4	2.9	50.0	49.5				341	135	21				28
6	Buck Williams B. Williams	187	3,195	39.2	17.7	17.1	1.7			6.7	12.1	55.2	0.0			4.4	6.5	67.4	59.3				7,333	3,308	324				641	+34
7	Joe Barry Carroll J. Barry Carroll	16	273	40.2	25.3	17.1	2.1	1.1	2.1	10.3	21.8	47.1	0.0	0.1	0.0	4.8	6.2	77.8	51.7	6.0	11.1	3.6	643	405	34	18	34	57	44
8	Robert Parish R. Parish	129	2,202	37.9	20.1	17.1	1.9			8.1	14.8	55.0	0.0	0.0		3.9	5.4	71.3	58.6				4,890	2,598	243				360
9	Dan Roundfield D. Roundfield	29	485	38.1	18.8	16.7	3.1		1.9	6.7	15.0	44.9	0.0	0.2	0.0	5.3	7.2	74.2	51.8				1,104	545	91		54		92
10	Larry Smith L. Smith	89	1,554	35.6	10.6	17.5	1.5	1.0	0.8	4.5	8.8	51.5	0.0	0.0	0.0	1.6	2.9	55.5	52.9	7.3	10.2	1.8	3,167	943	134	93	70	156	350
11	Bill Laimbeer B. Laimbeer	165	2,850	38.0	18.2	17.3	2.5			7.1	14.1	50.5	0.1	0.4	32.9	3.8	4.5	84.9	56.7				6,265	3,005	408				570
12	Eddie Johnson E. Johnson	1	15	39.0	34.0	15.0	1.0	1.0	0.0	14.0	22.0	63.6	0.0	0.0		6.0	9.0	66.7	65.5	7.0	8.0	3.0	39	34	1	1	0	3	4
13	Jack Sikma J. Sikma	68	1,176	38.7	20.5	17.3	4.0	1.2	1.3	7.1	15.9	44.8	0.1	0.3	19.0	6.2	7.0	88.4	54.0	4.4	12.9	2.8	2,634	1,396	271	83	88	192	252
14	Kent Benson K. Benson	3	45	35.0	16.0	15.0	4.7	1.0	0.7	7.0	12.3	56.8	0.0	0.0		2.0	3.3	60.0	58.0	5.0	10.0	4.0	105	48	14	3	2	12	11
15	Magic Johnson M. Johnson	9	144	40.3	18.7	16.0	14.8			6.2	13.8	45.2	0.4	1.7	26.7	5.8	6.1	94.5	56.7				363	168	133				23
16	Larry Bird L. Bird	61	1,008	41.3	26.8	16.5	7.0			10.1	21.5	46.8	0.7	2.1	35.2	5.9	6.7	87.6	54.7				2,521	1,635	425				142
17	Pat Cummings P. Cummings	18	295	34.7	16.7	16.4	1.7	0.8	0.7	6.4	13.9	46.0	0.0	0.1	0.0	3.9	5.4	71.4	51.2	5.3	11.1	3.3	624	300	31	14	13	59	66
18	Jeff Ruland J. Ruland	47	767	42.3	22.4	16.3	3.6			8.3	14.7	56.5	0.0			5.7	8.2	69.6	61.0				1,987	1,051	171				180
19	Terry Cummings T. Cummings	45	762	37.9	25.0	16.9	2.5		0.8	10.2	21.4	47.8	0.1			4.4	6.2	72.2	51.8				1,704	1,126	113		35		173	+2
20	Clark Kellogg C. Kellogg	23	397	38.0	24.9	17.3	4.0	2.0	0.8	10.0	19.9	50.2	0.1	0.3	33.3	4.8	5.7	84.0	55.5				874	572	91	45	18		83
21	Cliff Robinson C. Robinson	40	688	39.0	22.8	17.2	2.3			9.3	19.5	47.8	0.0	0.1	33.3	4.2	5.6	74.2	51.9				1,561	912	90				118
22	Major Jones M. Jones	2	31	26.0	10.5	15.5	1.5			4.5	10.5	42.9	0.0	0.0		1.5	3.0	50.0	44.4				52	21	3				7
23	Kareem Abdul-Jabbar K. Abdul-Jabbar	3	47	34.3	25.3	15.7	5.7	0.3	3.0	10.0	18.7	53.6	0.0	0.0		5.3	8.0	66.7	57.1	6.0	9.7	4.3	103	76	17	1	9	13	10
24	Dave Greenwood D. Greenwood	40	691	38.2	14.8	17.3	2.7		1.1	5.6	10.5	53.2	0.0	0.0	0.0	3.6	4.8	75.4	58.6				1,528	590	106		45		133
25	Kurt Rambis K. Rambis	22	362	33.3	13.1	16.5	2.5	1.5	1.4	5.1	9.3	54.9	0.0	0.0	0.0	3.0	4.0	73.0	59.4	6.5	10.0	1.8	732	289	54	33	30	40	64