strange coll behavior

hello,

seem to be getting some strange coll behavior. i insert this list via the coll editor ui:

0, centre 40 lo 35.5 hi 44.7;
1, centre 50 lo 44.7 hi 56.2;
2, centre 63 lo 56.2 hi 70.8;
3, centre 80 lo 70.8 hi 89.1;
4, centre 100 lo 89.1 hi 112;
5, centre 125 lo 112 hi 141;
6, centre 160 lo 141 hi 178;
7, centre 200 lo 178 hi 224;
8, centre 250 lo 224 hi 282;
9, centre 315 lo 282 hi 355;
10, centre 400 lo 355 hi 447;
11, centre 500 lo 447 hi 562;
12, centre 630 lo 562 hi 708;
13, centre 800 lo 708 hi 891;
14, centre 1000 lo 891 hi 1122;
15, centre 1250 lo 1122 hi 1413;
16, centre 1600 lo 1413 hi 1778;
17, centre 2000 lo 1778 hi 2239;

once i close the ui, and then reopen i get these values:

0, centre 40 lo 35.5 hi 44.700001;
1, centre 50 lo 44.700001 hi 56.200001;
2, centre 63 lo 56.200001 hi 70.800003;
3, centre 80 lo 70.800003 hi 89.099998;
4, centre 100 lo 89.099998 hi 112;
5, centre 125 lo 112 hi 141;
6, centre 160 lo 141 hi 178;
7, centre 200 lo 178 hi 224;
8, centre 250 lo 224 hi 282;
9, centre 315 lo 282 hi 355;
10, centre 400 lo 355 hi 447;
11, centre 500 lo 447 hi 562;
12, centre 630 lo 562 hi 708;
13, centre 800 lo 708 hi 891;
14, centre 1000 lo 891 hi 1122;
15, centre 1250 lo 1122 hi 1413;
16, centre 1600 lo 1413 hi 1778;
17, centre 2000 lo 1778 hi 2239;

why is coll adding small decimal values to the input? seems to only occur with floats...

thanks. j